2,1

G.f.: x^2[10-6x-40x^2]/[1-4x)(1-4x^2)].

Equals 2^(2[n/2]-1) * (A056450(n)+1). Cf. A001445.

Sequence in context: A166066 A068078 A067806 this_sequence A001890 A010818 A065195

Adjacent sequences: A001443 A001444 A001445 this_sequence A001447 A001448 A001449

nonn

N. J. A. Sloane (njas(AT)research.att.com).