A047486 Numbers that are congruent to {0, 1, 3, 5, 7} mod 8.

0, 1, 3, 5, 7, 8, 9, 11, 13, 15, 16, 17, 19, 21, 23, 24, 25, 27, 29, 31, 32, 33, 35, 37, 39, 40, 41, 43, 45, 47, 48, 49, 51, 53, 55, 56, 57, 59, 61, 63, 64, 65, 67, 69, 71, 72, 73, 75, 77, 79, 80, 81, 83, 85, 87, 88, 89

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Comments

Also nonnegative integers primitively represented by x^2 - y^2. - Ray Chandler, Aug 23 2014

Links

• Ray Chandler, Table of n, a(n) for n = 1..10000
• N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
• Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).

Crossrefs

Cf. A065091, A094572.

Formula

G.f.: x^2*(x^2 + 1)*(1 + x)^2/((x^4 + x^3 + x^2 + x + 1)*(x - 1)^2). - R. J. Mathar, Oct 07 2011

From Wesley Ivan Hurt, Dec 28 2016: (Start)

a(n) = a(n-1) + a(n-5) - a(n-6) for n > 6.

a(n) = (40*n - 40 - 2*(n mod 5) - 2*((n+1) mod 5) - 2*((n+2) mod 5) + 3*((n+3) mod 5) + 3*((n+4) mod 5))/25. (End)