A017090 a(n) = (8*n + 2)^2.

4, 100, 324, 676, 1156, 1764, 2500, 3364, 4356, 5476, 6724, 8100, 9604, 11236, 12996, 14884, 16900, 19044, 21316, 23716, 26244, 28900, 31684, 34596, 37636, 40804, 44100, 47524, 51076, 54756, 58564, 62500, 66564, 70756, 75076, 79524, 84100, 88804, 93636, 98596

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 (3,-3,1).

Crossrefs

Cf. A006752, A016814, A017089 (8n+2), A000290 (n^2).

Programs

Magma

[(8*n+2)^2: n in [0..35]]; // Vincenzo Librandi, Jul 12 2011

Mathematica

Table[(8*n + 2)^2, {n, 0, 40}] (* Amiram Eldar, Apr 24 2023 *)

PARI

a(n)=(8*n+2)^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: -4*(1 + 22*x + 9*x^2)/(x-1)^3. - R. J. Mathar, Jul 14 2016

From Amiram Eldar, Apr 24 2023: (Start)

a(n) = A017089(n)^2.

a(n) = 2^2*A016814(n).

Sum_{n>=0} 1/a(n) = Pi^2/64 + G/8, where G is Catalan's constant (A006752). (End)