A047276 Numbers that are congruent to {2, 6} mod 7.

2, 6, 9, 13, 16, 20, 23, 27, 30, 34, 37, 41, 44, 48, 51, 55, 58, 62, 65, 69, 72, 76, 79, 83, 86, 90, 93, 97, 100, 104, 107, 111, 114, 118, 121, 125, 128, 132, 135, 139, 142, 146, 149, 153, 156, 160, 163, 167, 170, 174, 177, 181, 184, 188, 191, 195, 198, 202, 205

Offset

1,1

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

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

Formula

a(n) = 7*n - a(n-1) - 6 (with a(1)=2). - Vincenzo Librandi, Aug 05 2010

G.f.: x*(2 + 4*x + x^2) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Oct 25 2011

a(n) = 3*n + floor(n/2) - 1. - Arkadiusz Wesolowski, Sep 19 2012

E.g.f.: 1 + ((14*x - 5)*exp(x) + exp(-x))/4. - David Lovler, Sep 12 2022

Prog

(PARI) a(n) = 3*n + floor(n/2) - 1 \\ David Lovler, Sep 12 2022

Crossrefs

Sequence in context: A184821 A292659 A184869 * A171639 A054770 A184745

Adjacent sequences: A047273 A047274 A047275 * A047277 A047278 A047279

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved