A047374 Numbers that are congruent to {4, 5} mod 7.

4, 5, 11, 12, 18, 19, 25, 26, 32, 33, 39, 40, 46, 47, 53, 54, 60, 61, 67, 68, 74, 75, 81, 82, 88, 89, 95, 96, 102, 103, 109, 110, 116, 117, 123, 124, 130, 131, 137, 138, 144, 145, 151, 152, 158, 159, 165, 166, 172

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

G.f.: x*(4 + x + 2*x^2)/((1 + x)*(x - 1)^2). - R. J. Mathar, Dec 04 2011

a(n) = -(5/4)*(-1)^n + 7*(n-1)/2 + 11/4. - Viet Quoc Le Tran, Jun 14 2014

a(n) = (14*n - 5*(-1)^n - 3)/4. - David Lovler, Sep 15 2022

E.g.f.: 2 + ((14*x - 3)*exp(x) - 5*exp(-x))/4. - David Lovler, Sep 15 2022

Mathematica

Select[Range[200], MemberQ[{4, 5}, Mod[#, 7]] &] (* Amiram Eldar, May 07 2021 *)

Prog

(PARI) a(n) = (14*n - 5*(-1)^n - 3)/4 \\ David Lovler, Sep 15 2022

Crossrefs

Cf. A017029, A017041.

Sequence in context: A372440 A261673 A027708 * A241653 A100107 A066828

Adjacent sequences: A047371 A047372 A047373 * A047375 A047376 A047377

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved