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A245265 E.g.f. satisfies: A(x) = exp(x/(1-x*A(x)^4)). 4
1, 1, 3, 37, 649, 15461, 471571, 17456041, 760880625, 38178439849, 2167446089251, 137359883836781, 9612722107574521, 736277501363180557, 61265207586681046131, 5503291392884323494961, 530778414439201798454881, 54706967800114521799571921, 6000952913613549583603208515 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Generally, if e.g.f. satisfies: A(x) = exp(x/(1-x*A(x)^p)), p>=1, then

r = 4*LambertW(sqrt(p)/2)^2 / (p*(1+2*LambertW(sqrt(p)/2))),

A(r) = (sqrt(p)/(2*LambertW(sqrt(p)/2)))^(2/p),

a(n) ~ p^(n-1+1/p) * (1+2*LambertW(sqrt(p)/2))^(n+1/2) * n^(n-1) / (sqrt(1+LambertW(sqrt(p)/2)) * exp(n) * 2^(2*n+2/p) * LambertW(sqrt(p)/2)^(2*n+2/p-1/2)).

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Vaclav Kotesovec, Asymptotic of sequences A161630, A212722, A212917 and A245265

FORMULA

a(n) = Sum_{k=0..n} n! * (1 + 4*(n-k))^(k-1)/k! * C(n-1,n-k).

a(n) ~ n^(n-1) * (1+2*LambertW(1))^(n+1/2) / (exp(n) * (LambertW(1))^(2*n) * (4*sqrt(1+LambertW(1)))). - Vaclav Kotesovec, Jul 15 2014

MATHEMATICA

Table[Sum[n! * (1 + 4*(n-k))^(k-1)/k! * Binomial[n-1, n-k], {k, 0, n}], {n, 0, 20}]

PROG

(PARI) for(n=0, 30, print1(sum(k=0, n, n!*(1 + 4*(n-k))^(k-1)/k!*binomial(n-1, n-k)), ", ")) \\ G. C. Greubel, Nov 17 2017

CROSSREFS

Cf. A161630 (p=1), A212722 (p=2), A212917 (p=3).

Cf. A030178.

Sequence in context: A216696 A333385 A331114 * A143639 A143412 A331656

Adjacent sequences:  A245262 A245263 A245264 * A245266 A245267 A245268

KEYWORD

nonn,easy

AUTHOR

Vaclav Kotesovec, Jul 15 2014

STATUS

approved

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Last modified April 19 15:32 EDT 2021. Contains 343116 sequences. (Running on oeis4.)