OFFSET
1,1
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 78.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
FORMULA
a(n) = A008287(2 * n, 3 * n - 1). - Sean A. Irvine, Aug 15 2016
MAPLE
seq(coeff((1+x+x^2+x^3)^(2*n), x, 3*n-1), n=1..30); # Robert Israel, Aug 15 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset changed by Robert Israel, Aug 15 2016
STATUS
approved