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A334262 E.g.f. A(x) satisfies: A(x) = 2 * x / (exp(A(x)) * (2 + A(x))). 1
1, -3, 21, -235, 3630, -71631, 1721671, -48804183, 1594177605, -58963348675, 2435865852156, -111169287046467, 5554808694622369, -301609325982387255, 17682700497003095625, -1113293610926803531951, 74915504280675843548274, -5365793673423031533999147 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Exponential reversion of A000217 (triangular numbers).

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 1..200

Index entries for reversions of series

FORMULA

a(n) ~ -(-1)^n * n^(n-1) / (2^(1/4) * (sqrt(2)-1)^(n - 1/2) * exp(n*(sqrt(2)-1))). - Vaclav Kotesovec, Apr 21 2020

MATHEMATICA

nmax = 18; CoefficientList[InverseSeries[Series[Exp[x] (x + x^2/2), {x, 0, nmax}], x], x] Range[0, nmax]! // Rest

PROG

(PARI) seq(n)= Vec(serlaplace(serreverse(sum(k=1, n, (k*(k+1)/2)*x^k/k!) + O(x*x^n)))); \\ Michel Marcus, Apr 21 2020

CROSSREFS

Cf. A000217, A066399, A179848.

Sequence in context: A179331 A138903 A302703 * A234855 A058562 A145083

Adjacent sequences:  A334259 A334260 A334261 * A334263 A334264 A334265

KEYWORD

sign

AUTHOR

Ilya Gutkovskiy, Apr 20 2020

STATUS

approved

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Last modified January 20 18:05 EST 2022. Contains 350472 sequences. (Running on oeis4.)