A047491 - OEIS

A047491

Numbers that are congruent to {4, 5, 7} mod 8.

4, 5, 7, 12, 13, 15, 20, 21, 23, 28, 29, 31, 36, 37, 39, 44, 45, 47, 52, 53, 55, 60, 61, 63, 68, 69, 71, 76, 77, 79, 84, 85, 87, 92, 93, 95, 100, 101, 103, 108, 109, 111, 116, 117, 119, 124, 125, 127, 132, 133, 135, 140, 141, 143, 148, 149, 151, 156, 157

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..59.

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

FORMULA

G.f.: x*(4+x+2*x^2+x^3)/((1+x+x^2)*(x-1)^2). - R. J. Mathar, Nov 06 2015

From Wesley Ivan Hurt, Jun 09 2016: (Start)

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

a(n) = (24*n-9*cos(2*n*Pi/3)+5*sqrt(3)*sin(2*n*Pi/3))/9.

a(3k) = 8k-1, a(3k-1) = 8k-3, a(3k-2) = 8k-4. (End)