A047346 Numbers that are congruent to {1, 4} mod 7.

1, 4, 8, 11, 15, 18, 22, 25, 29, 32, 36, 39, 43, 46, 50, 53, 57, 60, 64, 67, 71, 74, 78, 81, 85, 88, 92, 95, 99, 102, 106, 109, 113, 116, 120, 123, 127, 130, 134, 137, 141, 144, 148, 151, 155, 158, 162, 165, 169, 172, 176, 179, 183, 186, 190, 193, 197, 200, 204, 207, 211, 214

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Daniel Starodubtsev, Table of n, a(n) for n = 1..10000
• Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

Crossrefs

Cf. A001106.

Programs

Maple

A047346:=n->4*n-3-floor(n/2); seq(A047346(k),k=1..100); # Wesley Ivan Hurt, Oct 16 2013

Mathematica

Table[4n-3-Floor[n/2],{n,100}] (* Wesley Ivan Hurt, Oct 16 2013 *)

PARI

a(n) = 4*n-n\2-3; \\ Altug Alkan, Sep 10 2016

Formula

a(n) = floor( (7n-5)/2 ). - Santi Spadaro, Jul 24 2001

G.f.: x*(1 + 3*x + 3*x^2) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Dec 04 2011

a(n) = 4n - 3 - floor(n/2). - Wesley Ivan Hurt, Oct 16 2013

E.g.f.: 3 + ((14*x - 11)*exp(x) - exp(-x))/4. - David Lovler, Sep 01 2022