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Search: id:A001777
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| A001777 |
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Lah numbers: n!C(n-1,4)/5!.
(Formerly M5213 N2267)
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+0
4
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| 1, 30, 630, 11760, 211680, 3810240, 69854400, 1317254400, 25686460800, 519437318400, 10908183686400, 237996734976000, 5394592659456000, 126980411830272000, 3101950060425216000, 78582734864105472000
(list; graph; listen)
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OFFSET
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5,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 156.
J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 44.
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FORMULA
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E.g.f.: ((x/(1-x))^5)/5!.
If we define f(n,i,x)= sum(sum(binomial(k,j)*stirling1(n,k)*stirling2(j,i)*x^(k-j),j=i..k),k=i..n) then a(n+1)=(-1)^n*f(n,4,-6), (n>=4). [From Milan R. Janjic (agnus(AT)blic.net), Mar 01 2009]
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MAPLE
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A001777 := n-> n!*binomial(n-1, 4)/5!;
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PROGRAM
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(Other) sage: [binomial(n, 5)*factorial (n-1)/factorial (4) for n in xrange(5, 21)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jul 07 2009]
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CROSSREFS
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Column 5 of A008297. Cf. A053495.
Column m=5 of unsigned triangle A111596.
Sequence in context: A075911 A001719 A004359 this_sequence A136661 A111779 A075473
Adjacent sequences: A001774 A001775 A001776 this_sequence A001778 A001779 A001780
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Barbara Haas Margolius (margolius(AT)math.csuohio.edu)
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