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Quadrinomial coefficients.
(Formerly M3148)
0

%I M3148 #21 Oct 12 2017 19:24:11

%S 3,40,546,7728,112035,1650792,24608948,370084832,5603730876,

%T 85316186400,1304770191802,20029132137840,308437355259930,

%U 4762695514958640,73716196036213800,1143325208566357440,17765127399780725316,276484586847524844768,4309270265307160983144

%N Quadrinomial coefficients.

%D L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 78.

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

%H R. K. Guy, <a href="/A005712/a005712.pdf">Letter to N. J. A. Sloane, 1987</a>

%F a(n) = A008287(2 * n, 3 * n - 1). - _Sean A. Irvine_, Aug 15 2016

%p seq(coeff((1+x+x^2+x^3)^(2*n),x,3*n-1), n=1..30); # _Robert Israel_, Aug 15 2016

%Y Cf. A008287.

%K nonn

%O 1,1

%A _N. J. A. Sloane_

%E Offset changed by _Robert Israel_, Aug 15 2016