OFFSET
0,2
COMMENTS
G.f. for a(n)=A027472(n+3), n >= 0, is 1/(1-3*x)^3.
LINKS
W. Lang, On generalizations of Stirling number triangles, J. Integer Seqs., Vol. 3 (2000), #00.2.4.
Index entries for linear recurrences with constant coefficients, signature (9, -27, 27).
FORMULA
a(n) = 3^(n-1)*binomial(n+3, 2); G.f.: (-1+(1-3*x)^(-3))/(x*3^2)=(1-3*x+3*x^2)/(1-3*x)^3.
G.f.: F(4,1;2;3x); [From Paul Barry, Sep 03 2008]
D-finite with recurrence: (n+1)*a(n) +3*(-n-3)*a(n-1)=0. - R. J. Mathar, Jan 28 2020
MATHEMATICA
CoefficientList[Series[((1/(1-3x))^3-1)/(9x), {x, 0, 30}], x] (* Harvey P. Dale, Nov 26 2018 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
STATUS
approved