login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A206401 E.g.f. A(x) satisfies: exp(A(x)) = x + exp(3*A(x)^2/2), with A(0) = 0. 4
1, 2, 11, 126, 2049, 42012, 1047507, 30867540, 1049597685, 40441973328, 1741357779039, 82865509846776, 4318613855629605, 244629863660429712, 14965278826983897303, 983295107764013223504, 69061868853286423944249, 5163430410995824208371968 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..18.

FORMULA

E.g.f.: A(x) = Series_Reversion( exp(x) - exp(3*x^2/2) ).

a(n) ~ sqrt((3*s - 1)/(3 - 3*s + 9*s^2)) * n^(n-1) / (exp(s+1)-exp(3*s^2/2+1))^n, where s = 0.39177456704014800117... is the root of the equation 3*s*exp(3*s^2/2 - s) = 1. - Vaclav Kotesovec, Jan 12 2014

EXAMPLE

E.g.f.: A(x) = x + 2*x^2/2! + 11*x^3/3! + 126*x^4/4! + 2049*x^5/5! +...

where A( exp(x) - exp(3*x^2/2) ) = x.

Related expansions:

exp(A(x)) = 1 + x + 3*x^2/2! + 18*x^3/3! + 195*x^4/4! + 3090*x^5/5! +...

exp(3*A(x)^2/2) = 1 + 3*x^2/2! + 18*x^3/3! + 195*x^4/4! + 3090*x^5/5! +...

MATHEMATICA

Rest[CoefficientList[InverseSeries[Series[E^x - E^(3*x^2/2), {x, 0, 20}], x], x] * Range[0, 20]!] (* Vaclav Kotesovec, Jan 12 2014 *)

PROG

(PARI) {a(n)=local(X=x+x*O(x^n)); if(n<1, 0, n!*polcoeff(serreverse(exp(X)-exp(3*X^2/2)), n))}

for(n=0, 30, print1(a(n), ", "))

CROSSREFS

Cf. A138014, A206402, A206403, A206404, A206405.

Sequence in context: A269069 A224366 A279703 * A193207 A112864 A077391

Adjacent sequences:  A206398 A206399 A206400 * A206402 A206403 A206404

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Feb 07 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 20 02:47 EST 2018. Contains 299357 sequences. (Running on oeis4.)