OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (36,-343,792,-484).
FORMULA
G.f.: 2*(2 - 54*x + 343*x^2 - 396*x^3)/((1 - x)*(1 - 2*x)*(1 - 11*x)*(1 - 22*x)). [Bruno Berselli, Apr 17 2014]
a(n) = (1 + 2^n)*(1 + 11^n). [Bruno Berselli, Apr 17 2014]
MATHEMATICA
Total[#^Range[0, 20]&/@Divisors[22]]
Table[(1 + 2^n) (1 + 11^n), {n, 0, 20}] (* Bruno Berselli, Apr 17 2014 *)
LinearRecurrence[{36, -343, 792, -484}, {4, 36, 610, 11988}, 30] (* Harvey P. Dale, May 21 2014 *)
PROG
(Magma) [DivisorSigma(n, 22): n in [0..20]];
(Maxima) makelist((1+2^n)*(1+11^n), n, 0, 20); /* Bruno Berselli, Apr 17 2014 */
CROSSREFS
Cf. sum of n-th powers of divisors of even k: A000051 (k=2), A001576 (k=4), A034488 (k=6), A034496 (k=8), A034517 (k=10), A034660 (k=12), A141013 (k=14), A020514 (k=16), A034661 (k=18), A034662 (k=20), this sequence (k=22), A034664 (k=24), A241030 (k=26), A241031 (k=28), A241032 (k=30), A034665 (k=32), A034666 (k=36), A034667 (k=40), A034668 (k=48), A034669 (k=56), A020516 (k=64), A034671 (k=72), A034672 (k=96), A034673 (k=120), A034674 (k=128), A034675 (k=144).
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Apr 17 2014
STATUS
approved