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A000453
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Stirling numbers of the second kind, S(n,4).
(Formerly M4722 N2018)
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22
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1, 10, 65, 350, 1701, 7770, 34105, 145750, 611501, 2532530, 10391745, 42355950, 171798901, 694337290, 2798806985, 11259666950, 45232115901, 181509070050, 727778623825, 2916342574750, 11681056634501, 46771289738810, 187226356946265, 749329038535350
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OFFSET
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4,2
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COMMENTS
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Given a set {1,2,3,4}, a(n) is the number of occurrences where the first 2 comes after the first '1', the first '3' after the first '2' and the first '4' after the first '3' in a list of n+3. For example, a(1): 1234; a(2): 11234, 12134, 12314, 12341, 12234, 12324, 12342, 12334, 12343, 12344. Related to the cereal box problem. - Kevin Nowaczyk, Aug 02 2007
a(n) is the number of partitions of [n] into 4 nonempty subsets. - Enrique Navarrete, Aug 27 2021
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 835.
F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied Tables, Cambridge, 1966, p. 223.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
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FORMULA
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G.f.: x^4/((1-x)*(1-2*x)*(1-3*x)*(1-4*x)).
E.g.f.: (exp(x)-1)^4/4!.
a(n) = det(|s(i+4,j+3)|, 1 <= i,j <= n-4), where s(n,k) are Stirling numbers of the first kind. - Mircea Merca, Apr 06 2013
a(n) = 10*a(n-1) - 35*a(n-2) + 50*a(n-3) - 24*a(n-4). - Wesley Ivan Hurt, Oct 10 2021
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MAPLE
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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