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, 49284, 52441, 55696, 59049, 62500, 66049, 69696, 73441, 77284
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..10000
- Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
Programs
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Magma
[(7*n+5)^2: n in [0..40] ]; // Vincenzo Librandi, Jul 18 2011
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Mathematica
(7*Range[0, 50] + 5)^2 (* Paolo Xausa, Aug 22 2024 *)
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PARI
a(n)=(7*n+5)^2 \\ Charles R Greathouse IV, Feb 13 2017
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
E.g.f.: exp(x)*(25 + 119*x + 49*x^2). - Stefano Spezia, Aug 25 2024