A047347 - OEIS

A047347

Numbers that are congruent to {0, 1, 4} mod 7.

0, 1, 4, 7, 8, 11, 14, 15, 18, 21, 22, 25, 28, 29, 32, 35, 36, 39, 42, 43, 46, 49, 50, 53, 56, 57, 60, 63, 64, 67, 70, 71, 74, 77, 78, 81, 84, 85, 88, 91, 92, 95, 98, 99, 102, 105, 106, 109, 112, 113, 116, 119, 120, 123, 126, 127, 130, 133, 134, 137, 140, 141

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..62.

Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1).

FORMULA

G.f.: x^2*(1+3*x+3*x^2)/((1+x+x^2)*(x-1)^2). - R. J. Mathar, Oct 08 2011

From Wesley Ivan Hurt, Jun 10 2016: (Start)

a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.

a(n) = 7*n/3-3+4*sin(2*n*Pi/3)/(3*sqrt(3)).

a(3k) = 7k-3, a(3k-1) = 7k-6, a(3k-2) = 7k-7. (End)