A054603 a(n) = Sum_{d|4} phi(d)*n^(4/d).

0, 4, 24, 96, 280, 660, 1344, 2464, 4176, 6660, 10120, 14784, 20904, 28756, 38640, 50880, 65824, 83844, 105336, 130720, 160440, 194964, 234784, 280416, 332400, 391300, 457704, 532224, 615496, 708180, 810960, 924544, 1049664

Offset: 0

Author

N. J. A. Sloane, Apr 16 2000

Keywords

• nonn
• easy

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..10000
• Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Crossrefs

Row n=4 of A185651.

Programs

Mathematica

LinearRecurrence[{5,-10,10,-5,1},{0,4,24,96,280},40] (* Harvey P. Dale, Nov 29 2015 *)

Formula

a(n) = n^4 + n^2 + 2n.

G.f.: -4*x*(4*x^2+x+1)/(x-1)^5. [Colin Barker, Dec 21 2012]