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A235329 E.g.f. satisfies: A'(x) = A(x)^3 / A(-x) with A(0) = 1. 3
1, 1, 4, 22, 184, 1888, 24352, 364336, 6372352, 125098624, 2765195776, 67161837568, 1795080211456, 51946830487552, 1628857441189888, 54705106541123584, 1968709261466042368, 75262309701303402496, 3057220808668673081344, 131069643224297960046592 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..19.

FORMULA

E.g.f.: 1/(1 - 3*Series_Reversion( Integral 1/(1-9*x^2)^(1/3) dx ))^(1/3).

Limit n->infinity (a(n)/n!)^(1/n) = Pi*2^(5/3)/(sqrt(3)*GAMMA(2/3)^3) = 2.3191905339278567... - Vaclav Kotesovec, Jan 28 2014

EXAMPLE

E.g.f.: A(x) = 1 + x + 4*x^2/2! + 22*x^3/3! + 184*x^4/4! + 1888*x^5/5! +...

Related series.

A(x)^3 = 1 + 3*x + 18*x^2/2! + 144*x^3/3! + 1512*x^4/4! + 19224*x^5/5! +...

Note that 1 - 1/A(x)^3 is an odd function:

1 - 1/A(x)^3 = 3*x - 18*x^3/3! - 216*x^5/5! - 18144*x^7/7! - 3483648*x^9/9! +...

where Series_Reversion((1 - 1/A(x)^3)/3) = Integral 1/(1-9*x^2)^(1/3) dx.

MATHEMATICA

CoefficientList[1/(1 - 3*InverseSeries[Series[Integrate[1/(1-9*x^2)^(1/3), x], {x, 0, 20}], x])^(1/3), x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 28 2014 *)

PROG

(PARI) /* By definition A'(x) = A(x)^3 / A(-x): */

{a(n)=local(A=1); for(i=0, n, A=1+intformal(A^3/subst(A, x, -x) +x*O(x^n) )); n!*polcoeff(A, n)}

for(n=0, 25, print1(a(n), ", "))

(PARI) /* E.g.f. 1/(1 - 3*Series_Reversion(Integral (1-9*x)^(1/3) dx))^(1/3): */

{a(n)=local(A=1); A=1/(1-3*serreverse(intformal(1/(1-9*x^2 +x*O(x^n))^(1/3))))^(1/3); n!*polcoeff(A, n)}

for(n=0, 25, print1(a(n), ", "))

CROSSREFS

Cf. A235322, A235345.

Sequence in context: A125863 A004115 A222885 * A220231 A112370 A197961

Adjacent sequences:  A235326 A235327 A235328 * A235330 A235331 A235332

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jan 05 2014

STATUS

approved

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Last modified January 23 16:42 EST 2020. Contains 331172 sequences. (Running on oeis4.)