0,3

G.f.: 1/2+1/3/(1+2*t)-1/6/(4*t-1). a(n)=(4^n+(-1)^n*2^(n+1))/6 for n>0

{a(n)/4} for k>0 is A003683.

Sequence in context: A002470 A087261 A078236 this_sequence A076687 A045882 A051681

Adjacent sequences: A054878 A054879 A054880 this_sequence A054882 A054883 A054884

nonn,walk

Paolo Dominici (pl.dm(AT)libero.it), May 23 2000