1,2

Even-indexed terms, a(n) = 2^n; odd indexed terms, a(n) = 2^(n-1) + 2^(n-2).

G.f.: -x*(4*x+1+2*x^2)/(2*x-1)/(2*x+1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 14 2007

a(4) = 16 = sum or row 4 terms of triangle A133571: (5 + 5 + 5 + 1).

a(4) = 16 = 2^4.

a(7) = 96 = 2^6 + 2^5 = 64 + 32.

Cf. A133571.

Adjacent sequences: A133569 A133570 A133571 this_sequence A133573 A133574 A133575

Sequence in context: A044858 A120375 A025618 this_sequence A121852 A122537 A059736

nonn

Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 16 2007