A017042 a(n) = (7*n + 5)^2.

25, 144, 361, 676, 1089, 1600, 2209, 2916, 3721, 4624, 5625, 6724, 7921, 9216, 10609, 12100, 13689, 15376, 17161, 19044, 21025, 23104, 25281, 27556, 29929, 32400, 34969, 37636, 40401, 43264, 46225

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.: -(25 + 69*x + 4*x^2)/(x-1)^3. - R. J. Mathar, Jul 14 2016

Sum_{n>=0} 1/a(n) = psi'(5/7)/49 = 0.05601413956.. - R. J. Mathar, May 07 2024

Prog

(Magma) [(7*n+5)^2: n in [0..40] ]; // Vincenzo Librandi, Jul 18 2011
(PARI) a(n)=(7*n+5)^2 \\ Charles R Greathouse IV, Feb 13 2017

Crossrefs

Sequence in context: A184057 A235713 A072471 * A100255 A305269 A052501

Adjacent sequences: A017039 A017040 A017041 * A017043 A017044 A017045

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved