[go: up one dir, main page]
More Web Proxy on the site http://driver.im/
login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A262049
Sum of the palindromic primes dividing n (with repetition).
3
0, 2, 3, 4, 5, 5, 7, 6, 6, 7, 11, 7, 0, 9, 8, 8, 0, 8, 0, 9, 10, 13, 0, 9, 10, 2, 9, 11, 0, 10, 0, 10, 14, 2, 12, 10, 0, 2, 3, 11, 0, 12, 0, 15, 11, 2, 0, 11, 14, 12, 3, 4, 0, 11, 16, 13, 3, 2, 0, 12, 0, 2, 13, 12, 5, 16, 0, 4, 3, 14, 0, 12, 0, 2, 13
OFFSET
1,2
COMMENTS
a(p)=0 for primes p which are not in A002385.
The first runs of 2, 3 and 4 identical values start at a(5), a(370) and a(2776191), respectively. - Giovanni Resta, Sep 09 2015
FORMULA
Let n=product_i p(i)^e(i), then a(n)=sum_{i,p(i) in A002113} e(i)*p(i).
a(n) <= A001414(n).
MAPLE
A262049 := proc(n)
local a, d ;
a := 0 ;
for d in ifactors(n)[2] do
if isA002113(op(1, d)) then
a := a+op(1, d)*op(2, d) ;
end if;
end do:
a ;
end proc:
seq(A262049(n), n=1..120) ;
MATHEMATICA
palQ[n_] := Block[{d = IntegerDigits@ n}, d == Reverse@ d]; {0}~Join~
Table[Total@ Select[Flatten[Table[#1, {#2}] & @@@ FactorInteger@ n], palQ], {n, 2, 75}] (* Michael De Vlieger, Sep 09 2015 *)
Join[{0}, Table[Total[Times@@@Select[FactorInteger[n], PalindromeQ[#[[1]]]&]], {n, 2, 80}]] (* Harvey P. Dale, Sep 05 2022 *)
CROSSREFS
Sequence in context: A360269 A345423 A159303 * A337310 A001414 A134875
KEYWORD
nonn,base
AUTHOR
R. J. Mathar, Sep 09 2015
STATUS
approved