A187012 Antidiagonal sums of A103516.

1, 2, 5, 4, 8, 6, 11, 8, 14, 10, 17, 12, 20, 14, 23, 16, 26, 18, 29, 20, 32, 22, 35, 24, 38, 26, 41, 28, 44, 30, 47, 32, 50, 34, 53, 36, 56, 38, 59, 40, 62, 42, 65, 44, 68, 46, 71, 48, 74, 50, 77, 52, 80, 54, 83, 56, 86, 58, 89, 60, 92, 62, 95, 64

Offset

2,2

Comments

This sequence differs from A081556 at least for n=24 (see comment about n=24 in A081556).

Links

Vincenzo Librandi, Table of n, a(n) for n = 2..1000

Formula

a(n) = sum{k=0..floor(n/2), 0^(k(n-2k))*(n-k+1)}. - Paul Barry, Aug 30 2013

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

a(n) = A080512(n) - 1 for n>2.

Mathematica

CoefficientList[Series[(1 + 2 x + 3 x^2 - x^4)/((1 - x)^2 (1 + x)^2), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 24 2014 *)

Prog

(PARI) a(n) = sum(k=0, n\2, 0^(k*(n-2*k))*(n-k+1)); \\ Michel Marcus, Aug 30 2013

Crossrefs

Sequence in context: A206256 A093052 A081556 * A134079 A033686 A243973

Adjacent sequences: A187009 A187010 A187011 * A187013 A187014 A187015

Keyword

nonn,easy

Author

Michel Marcus, Aug 30 2013

Status

approved