A005724 Quadrinomial coefficients. (Formerly M3148)

3, 40, 546, 7728, 112035, 1650792, 24608948, 370084832, 5603730876, 85316186400, 1304770191802, 20029132137840, 308437355259930, 4762695514958640, 73716196036213800, 1143325208566357440, 17765127399780725316, 276484586847524844768, 4309270265307160983144

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

Table of n, a(n) for n=1..19.

R. K. Guy, Letter to N. J. A. Sloane, 1987

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

Cf. A008287.

Sequence in context: A355373 A337692 A331795 * A215196 A093376 A051571

Adjacent sequences: A005721 A005722 A005723 * A005725 A005726 A005727

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Offset changed by Robert Israel, Aug 15 2016

Status

approved