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A027408 Number of labeled servers of dimension 21. 1
1, 21, 651, 25151, 1141791, 58999227, 3398446177, 215000489757, 14773746912897, 1093126139653877, 86488314164428659, 7275617735214635079, 647633785826931486079, 60753264284081214177339 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

R. Donaghey, Binomial self-inverse sequences and tangent coefficients, J. Combin. Theory, Series A, 21 (1976), 155-163.

FORMULA

E.g.f.: exp( sum( ((1+x)^i-1)/i, i=1..21 ) ).

MATHEMATICA

Table[n!*SeriesCoefficient[E^(Sum[((1+x)^i - 1)/i, {i, 1, 21}]), {x, 0, n}], {n, 0, 20}] (* Vincenzo Librandi, Jan 01 2013 *)

CROSSREFS

Sequence in context: A163032 A209264 A012501 * A177840 A297312 A158216

Adjacent sequences:  A027405 A027406 A027407 * A027409 A027410 A027411

KEYWORD

nonn

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified November 16 19:17 EST 2019. Contains 329201 sequences. (Running on oeis4.)