A131508 2*A000027 (natural numbers) sandwiched by tripled A001477 (nonnegative numbers).

0, 0, 0, 2, 1, 1, 1, 4, 2, 2, 2, 6, 3, 3, 3, 8, 4, 4, 4, 10, 5, 5, 5, 12, 6, 6, 6, 14, 7, 7, 7, 16, 8, 8, 8, 18, 9, 9, 9, 20, 10, 10, 10, 22, 11, 11, 11, 24, 12, 12, 12, 26, 13, 13, 13, 28, 14, 14, 14, 30, 15, 15, 15, 32, 16, 16, 16, 34, 17, 17, 17, 36, 18, 18, 18, 38, 19, 19, 19, 40, 20

Offset: 0

Author

Paul Curtz, Aug 13 2007

Keywords

• nonn
• easy
• less

Links

• Muniru A Asiru, Table of n, a(n) for n = 0..5000

Programs

GAP

a:=[0,0,0,2,1,1,1,4];; for n in [9..85] do a[n]:=2*a[n-4]-a[n-8]; od; a; # Muniru A Asiru, Oct 24 2018

Maple

seq(coeff(series(x^3*(x^3+x^2+x+2)/(x^8-2*x^4+1),x,n+1), x, n), n = 0 .. 85); # Muniru A Asiru, Oct 24 2018

Formula

From Chai Wah Wu, Oct 24 2018: (Start)

a(n) = 2*a(n-4) - a(n-8) for n > 7.

G.f.: x^3*(x^3 + x^2 + x + 2)/(x^8 - 2*x^4 + 1). (End)