|
%I #18 Sep 08 2022 08:46:07
%S 6,56,1050,25112,655746,17766056,489541650,13599182072,379283617986,
%T 10599157616456,296486304875250,8297561014164632,232274972859656226,
%U 6502905234227329256,182070232515259616850,5097810928082584052792
%N Sum of n-th powers of divisors of 28.
%H Vincenzo Librandi, <a href="/A241031/b241031.txt">Table of n, a(n) for n = 0..200</a>
%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (56,-1043,8240,-29204,43904,-21952).
%F G.f.: 2*(3 - 140*x + 2086*x^2 - 12360*x^3 + 29204*x^4 - 21952*x^5)/((1 - x)*(1 - 2*x)*(1 - 4*x)*(1 - 7*x)*(1 - 14*x)*(1 - 28*x)).
%F a(n) = (4^n + 2^n + 1)*(7^n + 1).
%t Total[#^Range[0, 20] & /@ Divisors[28]] (* or *) Table[(4^n + 2^n + 1) (7^n + 1), {n, 0, 20}]
%o (Magma) [DivisorSigma(n, 28): n in [0..20]]; /* or */ [(4^n+2^n+1)*(7^n+1): n in [0..20]];
%Y Cf. A018254 (divisors of 28).
%Y Cf. similar sequence listed in A241029.
%K nonn,easy
%O 0,1
%A _Vincenzo Librandi_, Apr 17 2014
| 