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Search: id:A009014
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| A009014 |
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Has exponential generating function (1+x)/(1+x+x^2/2). |
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+0
1
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| 1, 0, -1, 3, -6, 0, 90, -630, 2520, 0, -113400, 1247400, -7484400, 0, 681080400, -10216206000, 81729648000, 0, -12504636144000, 237588086736000, -2375880867360000, 0, 548828480360160000, -12623055048283680000
(list; graph; listen)
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OFFSET
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0,4
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REFERENCES
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Ghislain R. Franssens, On a Number Pyramid Related to the Binomial, Deleham, Eulerian, MacMahon and Stirling number triangles, Journal of Integer Sequences, Vol. 9 (2006), Article 06.4.1.
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FORMULA
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E.g.f.: (1+x)/(1+x+x^2/2) = 1/cosh(ln(1+x)).
a(n) = -n*a(n-1)-n*(n-1)/2*a(n-2), a(0)=1, a(1)=0.
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MATHEMATICA
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1/Cosh[ Log[ 1+x ] ]
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PROGRAM
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(PARI) a(n)=-(2^-n)*n!*real((-1+I)^(n+1))
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CROSSREFS
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Sequence in context: A070297 A094674 A125287 this_sequence A009036 A021281 A034004
Adjacent sequences: A009011 A009012 A009013 this_sequence A009015 A009016 A009017
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KEYWORD
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sign,easy
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AUTHOR
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R. H. Hardin (rhhardin(AT)att.net)
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EXTENSIONS
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Extended with signs Mar 15 1997 by Olivier Gerard. Better description from Michael Somos
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