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

0,4

Links

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

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)

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

Prog

(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

Crossrefs

Sequence in context: A181876 A131505 A100092 * A305502 A308211 A140130

Adjacent sequences: A131505 A131506 A131507 * A131509 A131510 A131511

Keyword

nonn,easy,less

Author

Paul Curtz, Aug 13 2007

Status

approved