OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Amya Luo, Pattern Avoidance in Nonnesting Permutations, Undergraduate Thesis, Dartmouth College (2024). See p. 16.
Index entries for linear recurrences with constant coefficients, signature (5,-4).
FORMULA
a(n) = 4*a(n-1) - 1.
a(n) = 5*a(n-1) - 4*a(n-2).
G.f.: (4-5*x)/((1-x)*(1-4*x)). - Bruno Berselli, Nov 04 2011
E.g.f.: (1/3)*(11*exp(4*x) + exp(x)). - G. C. Greubel, Jan 19 2023
MATHEMATICA
LinearRecurrence[{5, -4}, {4, 15}, 31] (* G. C. Greubel, Jan 19 2023 *)
PROG
(Magma) [(11*4^n+1)/3: n in [0..30]];
(SageMath) [(11*4^n+1)/3 for n in range(31)] # G. C. Greubel, Jan 19 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 04 2011
STATUS
approved