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A001720
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n!/24.
(Formerly M3960 N1634)
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35
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1, 5, 30, 210, 1680, 15120, 151200, 1663200, 19958400, 259459200, 3632428800, 54486432000, 871782912000, 14820309504000, 266765571072000, 5068545850368000, 101370917007360000, 2128789257154560000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 4,2
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COMMENTS
| The asymptotic expansion of the higher order exponential integral E(x,m=1,n=5) ~ exp(-x)/x*(1 - 5/x + 30/x^2 - 210/x^3 + 1680/x^4 - 15120/x^5 + 151200/x^6 - 1663200/x^7 + ... ) leads to the sequence given above. See A163931 and A130534 for more information. [Johannes W. Meijer, Oct 20 2009]
a(n) = A173333(n,4). [From Reinhard Zumkeller, Feb 19 2010]
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REFERENCES
| Mitrinovic, D. S.; Mitrinovic, R. S.; Tableaux d'une classe de nombres relies aux nombres de Stirling. Univ. Beograd. Publ. Elektrotehn. Fak. Ser. Mat. Fiz. No. 77 1962, 77 pp.
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
| Vincenzo Librandi, Table of n, a(n) for n = 4..300
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 264
W. Lang, On generalizations of Stirling number triangles, J. Integer Seqs., Vol. 3 (2000), #00.2.4.
Alexsandar Petojevic, The Function vM_m(s; a; z) and Some Well-Known Sequences, Journal of Integer Sequences, Vol. 5 (2002), Article 02.1.7
Index to divisibility sequences
Index entries for sequences related to factorial numbers
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FORMULA
| E.g.f.: x^4/(1-x)^5.
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MATHEMATICA
| a[n_]:=n!/24; [From Vladimir Orlovsky, Dec 13 2008]
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PROG
| (MAGMA) [Factorial(n)/24: n in [4..25]]; // Vincenzo Librandi, Jul 20 2011
(PARI) a(n)=n!/24 \\ Charles R Greathouse IV, Jan 12 2012
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CROSSREFS
| Cf. A049459, A051338. a(n)= A049353(n-3, 1) (first column of triangle).
Sequence in context: A144180 A091122 A029587 * A051829 A058247 A137965
Adjacent sequences: A001717 A001718 A001719 * A001721 A001722 A001723
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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