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A007681 a(n) = (2*n+1)^2*n!.
(Formerly M4632)
0
1, 9, 50, 294, 1944, 14520, 121680, 1134000, 11652480, 130999680, 1600300800, 21115987200, 299376000000, 4539498163200, 73316942899200, 1256675067648000, 22784918188032000, 435717099417600000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

H. W. Gould, A class of binomial sums and a series transform, Utilitas Math., 45 (1994), 71-83.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..17.

H. W. Gould, A class of binomial sums and a series transform, Utilitas Math., 45 (1994), 71-83. (Annotated scanned copy)

FORMULA

E.g.f.: (1 + 6*x + x^2)/(1 - x)^3. - Ilya Gutkovskiy, May 12 2017

CROSSREFS

Sequence in context: A171480 A257589 A231413 * A279972 A115366 A188210

Adjacent sequences:  A007678 A007679 A007680 * A007682 A007683 A007684

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified October 17 07:05 EDT 2018. Contains 316276 sequences. (Running on oeis4.)