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Search: id:A000795
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| A000795 |
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Salie numbers: expansion of cosh x / cos x = Sum_{n >= 0} a(n)*x^(2n)/(2n)!.
(Formerly M2044 N0810)
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+0
10
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| 1, 2, 12, 152, 3472, 126752, 6781632, 500231552, 48656756992, 6034272215552, 929327412759552, 174008703107274752, 38928735228629389312, 10255194381004799025152, 3142142941901073853366272, 1107912434323301224813002752, 445427836895850552387642130432
(list; graph; listen)
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OFFSET
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0,2
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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. 86, Problem 32.
M. S. Krick, On the coefficients of cosh x / cos x, Math. Mag., 34 (1960), 37-40.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..100
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FORMULA
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a(n) = Sum(k=0..n, C(2n, 2k)*A000364(n-k) ). - DELEHAM Philippe (kolotoko(AT)wanadoo.fr), Dec 16 2003
a(n) = Sum_{k>=0} (-1)^(n+k)*2^(2n-k)*A065547(n, k). - DELEHAM Philippe (kolotoko(AT)wanadoo.fr), Feb 26 2004
a(n) = sum_{k>=0} A086646(n, k). - DELEHAM Philippe (kolotoko(AT)wanadoo.fr), Feb 26 2004
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EXAMPLE
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cosh x / cos x = Sum_{n=0..inf} a(n)*x^(2n)/(2n)! = 1+x^2+1/2*x^4+19/90*x^6+31/360*x^8+3961/113400*x^10+...
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CROSSREFS
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A005647(n) = a(n)/2^n.
Cf. A000364 A086646.
Sequence in context: A105558 A126777 A126345 this_sequence A085628 A053549 A139383
Adjacent sequences: A000792 A000793 A000794 this_sequence A000796 A000797 A000798
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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