0,3

A signed version of A001787(n) = n*2^(n-1).

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

(PARI) {a(n)=polcoeff(x*(1 - 4*x - 4*x^2)/(1 + 4*x^2 +x*O(x^n))^2, n)}

Cf. A118441 (triangle), A118443 (row sums); A118435, A001787.

Sequence in context: A097067 A139756 A001787 this_sequence A038592 A048776 A135248

Adjacent sequences: A118439 A118440 A118441 this_sequence A118443 A118444 A118445

sign

Paul D. Hanna (pauldhanna(AT)juno.com), Apr 28 2006