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A097342 Sum k=0..floor(n/2), Stirling2(n-k,k)3^k. 1
1, 0, 3, 3, 12, 30, 93, 300, 1038, 3810, 14781, 60375, 258807, 1160949, 5435652, 26502555, 134282406, 705720549, 3840542031, 21608662710, 125523530724, 751831408929, 4637611255422, 29428408797852, 191907975348210 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..24.

FORMULA

a(n)=sum{k=0..floor(n/2), sum{i=0..k, (-1)^(k+i)i^(n-k)/(i!(k-i)!)}3^k }

MATHEMATICA

Table[Sum[StirlingS2[n-k, k]3^k, {k, 0, Floor[n/2]}], {n, 0, 30}] (* Harvey P. Dale, May 24 2012 *)

CROSSREFS

Cf. A024427, A097341.

Sequence in context: A268639 A192307 A161804 * A025236 A014432 A107330

Adjacent sequences:  A097339 A097340 A097341 * A097343 A097344 A097345

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Aug 05 2004

STATUS

approved

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Last modified February 21 07:18 EST 2018. Contains 299390 sequences. (Running on oeis4.)