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

1,2

Comments

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

Links

Table of n, a(n) for n=1..55.

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

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

Mathematica

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

Crossrefs

Cf. A146507, A146509, A146511, A146512.

Sequence in context: A282552 A278315 A175527 * A232524 A032827 A328465

Adjacent sequences: A146507 A146508 A146509 * A146511 A146512 A146513

Keyword

nonn

Author

Artur Jasinski, Oct 30 2008

Extensions

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

Formula and crossrefs corrected by Ray Chandler, Dec 06 2016

Status

approved