0,4

G.f. : (1-x)/(1-2x+x^2-3x^3); a(n)=2a(n-1)-a(n-2)+3a(n-3); a(n)=sum{k=0..floor(n/2), binomial(n-k, 2k)3^k }.

Sequence in context: A038418 A057318 A008118 this_sequence A155380 A155445 A133952

Adjacent sequences: A097113 A097114 A097115 this_sequence A097117 A097118 A097119

easy,nonn

Paul Barry (pbarry(AT)wit.ie), Jul 25 2004