2,1

G.f.: [x^2*(3-2x)*(1-x+x^2)]/(1-x)^4. Differences of A027966. - Ralf Stephan, Feb 07 2004

a(n+2) = A074742(n-1) = A008778(n)+2 = A000297(n-1)+3.

A column of triangle A027011.

Sequence in context: A103021 A025587 A101498 this_sequence A130145 A023552 A009859

Adjacent sequences: A027962 A027963 A027964 this_sequence A027966 A027967 A027968

nonn

Clark Kimberling (ck6(AT)evansville.edu)