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Search: id:A004282
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| 0, 3, 24, 100, 300, 735, 1568, 3024, 5400, 9075, 14520, 22308, 33124, 47775, 67200, 92480, 124848, 165699, 216600, 279300, 355740, 448063, 558624, 690000, 845000, 1026675, 1238328, 1483524, 1766100, 2090175
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OFFSET
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0,2
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FORMULA
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C(3+n, 2)*C(3+n, 3). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 10 2006
a(n-1) = sum {1 <= x_1, x_2 <= n} x_1*(det V(x_1,x_2))^2 = sum {1 <= i,j <= n} i*(i-j)^2, where V(x_1,x_2) is the Vandermonde matrix of order 2. - Peter Bala (pbala(AT)toucansurf.com), Sep 21 2007
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MAPLE
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[seq(numbperm (n, 2)*numbperm (n, 3)/12, n=2..31)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 26 2007
a:=n->sum(sum((n^3-n^2)/12, j=0..n), k=0..n): seq(a(n), n=1..30); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 09 2007
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CROSSREFS
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Cf. A006542, A107891, A114242.
Sequence in context: A027158 A117642 A092780 this_sequence A050545 A139031 A065692
Adjacent sequences: A004279 A004280 A004281 this_sequence A004283 A004284 A004285
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KEYWORD
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nonn
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AUTHOR
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njas
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