A251584 a(n) = 4^(n-2) * (n+1)^(n-4) * (3*n^2 + 13*n + 16).

1, 1, 6, 82, 1856, 59904, 2533888, 133169152, 8384643072, 616038400000, 51781055676416, 4903194794655744, 516634816527990784, 59967828129860288512, 7604226293760000000000, 1046004175955626414833664, 155145294199098982239567872, 24683771056652857103433596928, 4193546668531304927540807729152, 757730637305085952000000000000000

Offset: 0

Author

Paul D. Hanna, Dec 06 2014

Keywords

• nonn

Examples

			E.g.f.: A(x) = 1 + x + 6*x^2/2! + 82*x^3/3! + 1856*x^4/4! + 59904*x^5/5! + ...
such that A(x) = exp( 4*x*A(x) * G(x*A(x))^3 ) / G(x*A(x))^3
where G(x) = 1 + x*G(x)^3 is the g.f. of A002293:
G(x) = 1 + x + 4*x^2 + 22*x^3 + 140*x^4 + 969*x^5 + 7084*x^6 + ...
RELATED SERIES.
Note that A(x) = F(x*A(x)) where F(x) = exp(4*x*G(x)^3)/G(x)^3,
F(x) = 1 + x + 4*x^2/2! + 40*x^3/3! + 712*x^4/4! + 18784*x^5/5! + ...
is the e.g.f. of A251574.
		

Links

• G. C. Greubel, Table of n, a(n) for n = 0..322

Crossrefs

Cf. A251574, A001764.

Cf. Variants: A251583, A251585, A251586, A251587, A251588, A251589, A251590.

Programs

Magma

[4^(n - 2)*(n + 1)^(n - 4)*(3*n^2 + 13*n + 16): n in [0..50]]; // G. C. Greubel, Nov 13 2017

Mathematica

Table[4^(n - 2)*(n + 1)^(n - 4)*(3*n^2 + 13*n + 16), {n, 0, 50}] (* G. C. Greubel, Nov 13 2017 *)

PARI

{a(n) = 4^(n-2) * (n+1)^(n-4) * (3*n^2 + 13*n + 16) }
for(n=0,20,print1(a(n),", "))

PARI

{a(n) = local(G=1,A=1); for(i=1,n, G=1+x*G^4 +x*O(x^n));for(i=1,n, A = exp(4*x*A * subst(G^3,x,x*A) ) / subst(G^3,x,x*A) ); n!*polcoeff(A, n)}
for(n=0, 20, print1(a(n), ", "))

Formula

Let G(x) = 1 + x*G(x)^4 be the g.f. of A002293, then the e.g.f. A(x) of this sequence satisfies:

(1) A(x) = exp( 4*x*A(x) * G(x*A(x))^3 ) / G(x*A(x))^3.

(2) A(x) = F(x*A(x)) where F(x) = exp(4*x*G(x)^3)/G(x)^3 is the e.g.f. of A251574.

(3) a(n) = [x^n/n!] F(x)^(n+1)/(n+1) where F(x) is the e.g.f. of A251574.

E.g.f.: -LambertW(-4*x) * (4 + LambertW(-4*x))^3 / (256*x). - Vaclav Kotesovec, Dec 07 2014