0,2

a(n)= (4^n)*stirling2(n+3, 3), n>=0, with stirling2(n, m)=A008277(n, m).

a(n)= (4^n-8*8^n+9*12^n)/2.

G.f.: 1/((1-4*x)*(1-8*x)*(1-12*x)). E.g.f.: diff((((exp(4*x)-1)/4)^3)/3!, x$3) = (exp(4*x)-8*exp(8*x)+9*exp(12*x))/2.

Third column of triangle A075499.

Cf. A016152, A075907.

Sequence in context: A019687 A020341 A021674 this_sequence A021314 A018206 A021304

Adjacent sequences: A019674 A019675 A019676 this_sequence A019678 A019679 A019680

nonn

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