A146510 Numbers congruent to {1, 4} mod 15.

1, 4, 16, 19, 31, 34, 46, 49, 61, 64, 76, 79, 91, 94, 106, 109, 121, 124, 136, 139, 151, 154, 166, 169, 181, 184, 196, 199, 211, 214, 226, 229, 241, 244, 256, 259, 271, 274, 286, 289, 301, 304, 316, 319, 331, 334, 346, 349, 361, 364, 376, 379, 391, 394, 406

Offset: 1

Author

Artur Jasinski, Oct 30 2008

Keywords

• nonn

Comments

Positive integers k such that Hypergeometric[k/5,(5-k)/5,1/2,3/4] = 2Cos[Pi/5].

Links

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

Crossrefs

Cf. A146507, A146509, A146511, A146512.

Programs

Mathematica

Select[Range[500],MemberQ[{1,4},Mod[#,15]]&] (* Harvey P. Dale, Jan 21 2016 *)

Formula

a(2k-1) = 15*(k-1)+1, a(2k) = 15*(k-1)+4, where k>0.

G.f.: x*(1 + 3*x + 11*x^2)/((1 - x)^2*(1 + x)). - Ilya Gutkovskiy, Dec 06 2016

E.g.f.: 11 + ((30*x - 35)*exp(x) - 9*exp(-x))/4. - David Lovler, Sep 08 2022

Extensions

Typo in name corrected by N. J. A. Sloane, Jan 21 2016

Formula and crossrefs corrected by Ray Chandler, Dec 06 2016