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Search: id:A005494
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| A005494 |
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E.g.f.: exp(3*z+exp(z)-1).
(Formerly M3540)
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+0
6
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| 1, 4, 17, 77, 372, 1915, 10481, 60814, 372939, 2409837, 16360786, 116393205, 865549453, 6713065156, 54190360453, 454442481041, 3952241526188, 35590085232519, 331362825860749, 3185554606447814, 31581598272055879, 322516283206446897
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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From expansion of falling factorials (binomial transform of A005493).
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REFERENCES
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E. G. Whitehead, Jr., Stirling number identities from chromatic polynomials, J. Combin. Theory, A 24 (1978), 314-317.
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LINKS
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J. W. Layman, The Hankel Transform and Some of its Properties, J. Integer Sequences, 4 (2001), #01.1.5.
N. J. A. Sloane, Transforms
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FORMULA
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a(n) = Sum_{i=0..n} 3^(n-i)*B(i)*binomial(n,i) where B(n) = Bell numbers A000110(n). - Fred Lunnon, Aug 04 2007
a(n) = exp(-1)*sum(k=>0, (k+3)^(n)/k!) - Gerald McGarvey (Gerald.McGarvey(AT)comcast.net), Jun 03 2004. May be rewritten as a(n)=sum(k^n*(k-1)*(k-2)/k!,k=3..infinity)/exp(1), which is a Dobinski-type relation for this sequence. - Karol A. Penson (penson(AT)lptl.jussieu.fr), Aug 18 2006
Define f_1(x),f_2(x),... such that f_1(x)=x^2*e^x, f_{n+1}(x)=diff(x*f_n(x),x), for n=2,3,.... Then a(n-1)=e^{-1}*f_n(1). - Milan R. Janjic (agnus(AT)blic.net), May 30 2008
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CROSSREFS
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Cf. A000110, A005493.
Sequence in context: A124325 A104455 A123952 this_sequence A053486 A110307 A089165
Adjacent sequences: A005491 A005492 A005493 this_sequence A005495 A005496 A005497
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KEYWORD
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nonn
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AUTHOR
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njas, Simon Plouffe (plouffe(AT)math.uqam.ca)
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