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Search: a158933 -id:a158933
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Decimal expansion of the sum of reciprocals of the products of 3 consecutive Fibonacci numbers.
+10
3
7, 1, 0, 8, 5, 5, 3, 5, 1, 4, 2, 9, 3, 2, 8, 4, 1, 6, 8, 8, 7, 6, 9, 4, 4, 9, 0, 3, 8, 4, 2, 7, 0, 8, 3, 3, 0, 4, 5, 1, 1, 8, 0, 4, 8, 4, 1, 0, 3, 0, 8, 6, 3, 9, 9, 7, 4, 9, 7, 3, 5, 1, 4, 9, 3, 6, 9, 6, 4, 2, 3, 8, 2, 6, 1, 1, 3, 5, 4, 4, 8, 4, 1, 7, 5, 8, 8, 4, 1, 6, 8, 1, 7, 1, 4, 8, 5, 8, 5, 7, 6, 8, 5, 4, 9
OFFSET
0,1
LINKS
Brother Alfred Brousseau, Summation of Infinite Fibonacci Series, The Fibonacci Quarterly, Vol. 7, No. 2 (1969), pp. 143-168.
R. S. Melham, On Some Reciprocal Sums of Brousseau: An Alternative Approach to That of Carlitz, Fibonacci Quarterly, Vol. 41, No. 1 (2003), pp. 59-62.
FORMULA
From Amiram Eldar, Feb 09 2023: (Start)
Equals Sum_{k>=1} 1/A065563(k).
Equals 1 - A158933 (Melham, 2003). (End)
EXAMPLE
0.71085535142932841688769449038427083304511804841030863997497351493696423826...
MATHEMATICA
RealDigits[ Sum[ N[ 1/Product[ Fibonacci@j, {j, k, k + 2}], 128], {k, 177}], 10, 111][[1]]
PROG
(PARI) suminf(n=1, 1/(fibonacci(n)*fibonacci(n+1)*fibonacci(n+2))) \\ Michel Marcus, Feb 19 2019
KEYWORD
nonn,cons
AUTHOR
Robert G. Wilson v, Feb 11 2019
STATUS
approved
Decimal expansion of Sum_{n>=1} 1/F(n)^n, where F=A000045 (Fibonacci numbers).
+10
2
2, 1, 3, 7, 6, 6, 9, 5, 0, 9, 6, 7, 2, 6, 9, 8, 4, 3, 3, 3, 1, 7, 1, 4, 9, 8, 1, 6, 9, 0, 3, 2, 6, 1, 9, 4, 1, 9, 0, 3, 9, 6, 6, 6, 3, 1, 7, 4, 4, 2, 0, 9, 7, 5, 8, 4, 7, 2, 1, 2, 1, 4, 7, 1, 0, 5, 2, 3, 8, 7, 1, 0, 1, 1, 6, 3, 4, 5, 5, 0, 5, 2, 5, 3, 9, 6, 5, 8, 8, 6, 2, 6, 3, 0, 5, 3, 3, 3, 6, 6, 0, 8, 6, 8, 0
OFFSET
1,1
EXAMPLE
2.13766950967269843331714981... = 1/1^1 + 1/1^2+ 1/2^3+ 1/3^4 +1/5^5 +1/8^6 +...
MAPLE
with(combinat, fibonacci):Digits:=120:s:=sum( evalf(1/ fibonacci(n)^n), n=1..200):print(s):
MATHEMATICA
digits = 105; NSum[1/Fibonacci[n]^n, {n, 1, Infinity}, NSumTerms -> digits, WorkingPrecision -> digits] // RealDigits[#, 10, digits]& // First (* Jean-François Alcover, Feb 21 2014 *)
PROG
(PARI) suminf(n=1, 1/fibonacci(n)^n); \\ Michel Marcus, Feb 21 2014
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Michel Lagneau, Dec 03 2011
STATUS
approved
Decimal expansion of Sum_{n = 1 .. infinity} (-1)^(n+1)/F(n)^n where F=A000045 is the Fibonacci sequence.
+10
1
1, 1, 2, 9, 7, 0, 5, 2, 2, 2, 0, 0, 5, 9, 7, 7, 4, 2, 2, 3, 8, 0, 4, 0, 6, 7, 7, 9, 0, 4, 2, 8, 7, 9, 4, 3, 4, 0, 8, 6, 1, 9, 1, 4, 5, 0, 2, 3, 1, 6, 4, 4, 8, 6, 2, 1, 1, 2, 1, 0, 5, 0, 7, 6, 7, 7, 7, 0, 1, 9, 5, 3, 8, 3, 2, 7, 3, 0, 7, 9, 8, 9, 2, 9, 2, 6, 3, 4, 6, 4, 8, 2, 2, 8, 9, 4, 3, 8, 9, 6, 9, 3, 7, 8, 8
OFFSET
0,3
EXAMPLE
0.1129705222005977422380406779... = 1/1^1 - 1/1^2 + 1/2^3 - 1/3^4 + 1/5^5 - ...
MAPLE
with(combinat, fibonacci):Digits:=120:s:=sum( evalf(((-1)^(n+1))/ fibonacci(n)^n), n=1..200):print(s):
MATHEMATICA
RealDigits[N[Sum[((-1)^(n+1))/Fibonacci[n]^n, {n, 1, 105}], 105]][[1]]
PROG
(PARI) -suminf(n=1, (-1)^n/fibonacci(n)^n) \\ Charles R Greathouse IV, Dec 05 2011
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Michel Lagneau, Dec 03 2011
STATUS
approved
Decimal expansion of Sum_{k>=1} (-1)^(k+1)/L(k) where L(k) is the k-th Lucas number (A000032).
+10
1
8, 3, 0, 5, 0, 2, 8, 2, 1, 5, 8, 6, 8, 7, 6, 6, 8, 2, 3, 1, 6, 9, 3, 6, 4, 8, 6, 2, 5, 1, 0, 5, 9, 5, 1, 9, 1, 7, 7, 3, 0, 4, 6, 2, 1, 4, 3, 0, 4, 0, 8, 2, 8, 0, 1, 4, 6, 0, 2, 6, 4, 1, 3, 9, 0, 7, 9, 1, 0, 4, 9, 8, 4, 8, 6, 0, 4, 3, 0, 0, 6, 7, 4, 9, 3, 3, 0
OFFSET
0,1
COMMENTS
André-Jeannin (1989) proved that this constant is irrational, and Tachiya (2004) proved that it does not belong to the quadratic number field Q(sqrt(5)).
LINKS
Richard André-Jeannin, Irrationalité de la somme des inverses de certaines suites récurrentes, Comptes Rendus de l'Académie des Sciences - Series I - Mathematics, Vol. 308, No. 19 (1989), pp. 539-541.
Yohei Tachiya, Irrationality of certain Lambert series, Tokyo Journal of Mathematics, Vol. 27, No. 1 (2004), pp. 75-85.
Eric Weisstein's World of Mathematics, Reciprocal Lucas Constant.
FORMULA
Equals A153416 - A153415.
Equals Sum_{k>=1} (-1)^(k+1) * Fibonacci(k)/Fibonacci(2*k).
Equals Sum_{k>=1} (-1)^(k+1)/(phi^k + (1-phi)^k), where phi is the golden ratio (A001622).
Equals Sum_{k>=0} 1/(phi^(2*k+1) + (-1)^k).
EXAMPLE
0.83050282158687668231693648625105951917730462143040...
MATHEMATICA
RealDigits[Sum[(-1)^(n+1)/LucasL[n], {n, 1, 1000}], 10, 120][[1]]
KEYWORD
nonn,cons
AUTHOR
Amiram Eldar, Nov 03 2020
STATUS
approved
Decimal expansion of Sum_{k>=1} (-1)^(k+1)*k/Fibonacci(2*k).
+10
1
5, 8, 0, 0, 0, 4, 7, 3, 9, 5, 0, 7, 7, 7, 0, 6, 8, 0, 0, 6, 7, 4, 7, 0, 9, 8, 1, 8, 9, 5, 5, 2, 2, 8, 0, 2, 6, 9, 8, 5, 0, 1, 2, 6, 0, 9, 6, 4, 6, 1, 6, 3, 9, 0, 1, 5, 7, 7, 5, 6, 1, 0, 0, 1, 7, 7, 6, 7, 3, 7, 5, 7, 5, 2, 1, 9, 9, 7, 8, 4, 8, 9, 4, 9, 2, 1, 0, 4, 4, 7, 8, 6, 6, 9, 4, 0, 2, 2, 3, 7, 1, 4, 1, 1, 5
OFFSET
0,1
LINKS
Daniel Duverney and Iekata Shiokawa, On series involving Fibonacci and Lucas numbers I, AIP Conference Proceedings, Vol. 976, No. 1. American Institute of Physics, 2008, pp. 62-76.
Derek Jennings, On reciprocals of Fibonacci and Lucas numbers, Fibonacci Quarterly, Vol. 32, No. 1 (1994), pp. 18-21.
FORMULA
Equals Sum_{k>=1} (-1)^(k+1)*k/A001906(k).
Equals (1/sqrt(5)) * Sum_{k>=1} 1/Fibonacci(2*k-1)^2 (Jennings, 1994).
EXAMPLE
0.58000473950777068006747098189552280269850126096461...
MATHEMATICA
RealDigits[Sum[(-1)^(k+1)*k/Fibonacci[2*k], {k, 1, 300}], 10, 100][[1]]
PROG
(PARI) sumalt(k=1, (-1)^(k+1)*k/fibonacci(2*k)) \\ Michel Marcus, Sep 10 2022
KEYWORD
nonn,cons
AUTHOR
Amiram Eldar, Sep 10 2022
STATUS
approved

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