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A055142 E.g.f.: exp(x)*sqrt(1-2x). 5
1, 0, -2, -8, -36, -224, -1880, -19872, -251888, -3712256, -62286624, -1171487360, -24402416192, -557542291968, -13861636770176, -372514645389824, -10759590258589440, -332386419622387712 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

FORMULA

Column 0 of triangle A055141.

a(n) ~ -2^(n-1/2) * n^(n-1) / exp(n-1/2). - Vaclav Kotesovec, Mar 29 2014

MATHEMATICA

CoefficientList[Series[E^x*Sqrt[1-2*x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Mar 29 2014 *)

PROG

(Sage)

def A055142(n):

    @CachedFunction

    def h(n):

        return (-1)^n*2*(n-2)*abs(h(n-1)+h(n-2)) if n>1 else 1

    return -(-1)^(n+1)*h(n+1)

[A055142(n) for n in (0..17)]  # Peter Luschny, Nov 02 2012

CROSSREFS

Cf. A001147.

Sequence in context: A233744 A222469 A052618 * A183908 A280119 A224032

Adjacent sequences:  A055139 A055140 A055141 * A055143 A055144 A055145

KEYWORD

sign

AUTHOR

Christian G. Bower, May 09 2000

STATUS

approved

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Last modified October 15 20:17 EDT 2018. Contains 316237 sequences. (Running on oeis4.)