A034662 Sum of n-th powers of divisors of 20.

6, 42, 546, 9198, 170898, 3304182, 65019786, 1290094638, 25700456418, 513002215782, 10250010815226, 204900053024478, 4097000260921938, 81930001287820182, 1638500006371967466, 32769000031591352718, 655370000156882923458

Offset

0,1

Links

T. D. Noe, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (42,-609,3948,-12180,16800,-8000).

Formula

a(n) = (1 + 2^n + 4^n)*(1 + 5^n). - Bruno Berselli, Apr 17 2014

G.f.: -6*(2800*x^5 -4060*x^4 +1974*x^3 -406*x^2 +35*x -1) / ((x -1)*(2*x -1)*(4*x -1)*(5*x -1)*(10*x -1)*(20*x -1)). - Colin Barker, Apr 20 2014

Mathematica

Total[#^Range[0, 20]&/@Divisors[20]] (* Vincenzo Librandi, Apr 17 2014 *)
Table[(1 + 2^n + 4^n) (1 + 5^n), {n, 0, 20}] (* Bruno Berselli, Apr 17 2014 *)

Prog

(Sage) [sigma(20, n) for n in range(0, 16)] # Zerinvary Lajos, Jun 04 2009
(Magma) [DivisorSigma(n, 20): n in [0..20]]; // Vincenzo Librandi, Apr 17 2014

Crossrefs

Sequence in context: A254529 A098461 A284161 * A074651 A330345 A273922

Adjacent sequences: A034659 A034660 A034661 * A034663 A034664 A034665

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved