A017203 a(n) = (9*n + 3)^7.

2187, 35831808, 1801088541, 21870000000, 137231006679, 587068342272, 1954897493193, 5455160701056, 13348388671875, 29509034655744, 60170087060757, 114868566764928, 207616015289871, 358318080000000, 594467302491009, 953133216331392, 1483273860320763, 2248392813428736

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..10000
• Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).

Crossrefs

Cf. A013665, A016783, A017197.

Programs

Magma

[(9*n+3)^7: n in [0..20]]; // Vincenzo Librandi, Jul 23 2011

Mathematica

Table[(9*n + 3)^7, {n, 0, 20}] (* Amiram Eldar, Oct 03 2024 *)

Formula

From Amiram Eldar, Oct 03 2024: (Start)

a(n) = A017197(n)^7 = 3^7 * A016783(n).

Sum_{n>=0} 1/a(n) = 28*Pi^7/(215233605*sqrt(3)) + 1093*zeta(7)/4782969. (End)