OFFSET
0,2
LINKS
FORMULA
For n >= 1, a(n) = 4*n*3^n. - Robert Israel, May 08 2014
PROG
(Magma) m:=30; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((1+3*x)^2/(1-3*x)^2));
CROSSREFS
Cf. Expansion of (1 + k*x)^m/(1 - k*x)^m where the values of k,m are:
......|..m = 1..|..m = 2..|..m = 3..|..m = 4..|..m = 5..|..m = 6..|
k = 4 | A081654 | | | | | |
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KEYWORD
nonn,easy
AUTHOR
Ilya Lopatin and Juri-Stepan Gerasimov, Apr 22 2014
EXTENSIONS
Edited by Wolfdieter Lang, May 07 2014
STATUS
approved