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A017090
a(n) = (8*n + 2)^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
0,1
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)
MATHEMATICA
Table[(8*n + 2)^2, {n, 0, 40}] (* Amiram Eldar, Apr 24 2023 *)
PROG
(Magma) [(8*n+2)^2: n in [0..35]]; // Vincenzo Librandi, Jul 12 2011
(PARI) a(n)=(8*n+2)^2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
Cf. A006752, A016814, A017089 (8n+2), A000290 (n^2).
Sequence in context: A091268 A326085 A158082 * A029995 A365608 A244352
KEYWORD
nonn,easy
STATUS
approved