A017006 a(n) = (7*n+2)^2.

4, 81, 256, 529, 900, 1369, 1936, 2601, 3364, 4225, 5184, 6241, 7396, 8649, 10000, 11449, 12996, 14641, 16384, 18225, 20164, 22201, 24336, 26569, 28900, 31329, 33856, 36481, 39204, 42025, 44944, 47961

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Formula

G.f.: ( -4-69*x-25*x^2 ) / (x-1)^3 . - R. J. Mathar, Mar 21 2016

Sum_{n>=0} 1/a(n) = psi'(2/7)/49 = 0.27350250491707580.. - R. J. Mathar, May 07 2024

Prog

(Magma) [(7*n+2)^2: n in [0..40]]; // Vincenzo Librandi, Jul 13 2011
(PARI) a(n) = (7*n+2)^2; \\ Altug Alkan, Mar 21 2016

Crossrefs

Sequence in context: A072363 A272884 A053901 * A041189 A123198 A202831

Adjacent sequences: A017003 A017004 A017005 * A017007 A017008 A017009

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved