OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (42,-457,1092,-676).
FORMULA
G.f.: 2*(2 - 63*x + 457*x^2 - 546*x^3)/((1 - x)*(1 - 2*x)*(1 - 13*x)*(1 - 26*x)).
a(n) = (1 + 2^n)*(1 + 13^n).
MATHEMATICA
Total[#^Range[0, 20] & /@ Divisors[26]] (* or *) Table[(1 + 2^n) (1 + 13^n), {n, 0, 20}]
PROG
(Magma) [DivisorSigma(n, 26): n in [0..20]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Apr 17 2014
STATUS
approved