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Search: id:A061927
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| A061927 |
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n(n+1)(2n+1)(n^2+n+3)/30. |
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+0
3
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| 0, 1, 9, 42, 138, 363, 819, 1652, 3060, 5301, 8701, 13662, 20670, 30303, 43239, 60264, 82280, 110313, 145521, 189202, 242802, 307923, 386331, 479964, 590940, 721565, 874341, 1051974, 1257382, 1493703, 1764303, 2072784, 2422992, 2819025
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Also number of magic labelings of the cubical graph of magic sum n-1 [Ahmed]. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 25 2007
If Y_i (i=1,2,3) are 2-blocks of a (n+3)-set X then a(n-4) is the number of 8-subsets of X intersecting each Y_i (i=1,2,3). - Milan R. Janjic (agnus(AT)blic.net), Oct 28 2007
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LINKS
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Harry J. Smith, Table of n, a(n) for n=0,...,1000
Milan Janjic, Two Enumerative Functions
M. M. Ahmed, Algebraic Combinatorics of Magic Squares, math.CO/0405476, p73.
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FORMULA
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a(n) = a(n-1)+A014820(n) = A061926(9, n).
G.f.: x*(1+x)^3/(-1+x)^6 = 20/(-1+x)^5+1/(-1+x)^2+7/(-1+x)^3+18/(-1+x)^4+8/(-1+x)^6 . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 18 2007
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PROGRAM
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(PARI) { for (n=0, 1000, write("b061927.txt", n, " ", n*(n + 1)*(2*n + 1)*(n^2 + n + 3)/30) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 29 2009]
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CROSSREFS
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Sequence in context: A062783 A027441 A000971 this_sequence A051923 A084899 A074443
Adjacent sequences: A061924 A061925 A061926 this_sequence A061928 A061929 A061930
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KEYWORD
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nonn
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), May 17 2001
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