0,2

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

a(n)= (3^n-8*6^n+9*9^n)/2.

G.f.: 1/((1-3*x)*(1-6*x)*(1-9*x)). E.g.f.: diff((((exp(3*x)-1)/3)^3)/3!, x$3) = (exp(3*x)-8*exp(6*x)+9*exp(9*x))/2.

Third column of triangle A075498.

Cf. A016137, A028085.

Sequence in context: A017997 A018911 A021194 this_sequence A021384 A056950 A021144

Adjacent sequences: A017930 A017931 A017932 this_sequence A017934 A017935 A017936

nonn

njas