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Search: id:A006974
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| A006974 |
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Coefficients of Chebyshev polynomials.
(Formerly M4631)
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+0
6
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| 1, 9, 50, 220, 840, 2912, 9408, 28800, 84480, 239360, 658944, 1770496, 4659200, 12042240, 30638080, 76873728, 190513152, 466944000, 1133117440, 2724986880, 6499598336, 15386804224, 36175872000, 84515225600, 196293427200, 453437816832
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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If X_1,X_2,...,X_n are 2-blocks of a (2n+1)-set X then, for n>=3, a(n-3) is the number of (n+4)-subsets of X intersecting each X_i, (i=1,2,...,n). - Milan R. Janjic (agnus(AT)blic.net), Nov 18 2007
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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. 795.
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LINKS
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Milan Janjic, Two Enumerative Functions
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, December 1972 [alternative scanned copy].
Index entries for sequences related to Chebyshev polynomials.
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FORMULA
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G.f.: (1-x)/(1-2*x)^5.
a(n)=sum{k=0..floor((n+8)/2), C(n+8, 2k)C(k, 4) } - Paul Barry (pbarry(AT)wit.ie), May 15 2003
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MAPLE
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a := n->n*(n+1)*(n+2)*(n+7)*2^(n-5)/3;
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CROSSREFS
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a(n)= A039991(n+8, 8).
Adjacent sequences: A006971 A006972 A006973 this_sequence A006975 A006976 A006977
Sequence in context: A080812 A116169 A084367 this_sequence A007681 A115366 A002462
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KEYWORD
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nonn,easy
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AUTHOR
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Simon Plouffe (plouffe(AT)math.uqam.ca)
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