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Search: id:A062026
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| A062026 |
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a(n) = n(n+1)(n^2 -3n +6)/4 |
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+0
3
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| 0, 2, 6, 18, 50, 120, 252, 476, 828, 1350, 2090, 3102, 4446, 6188, 8400, 11160, 14552, 18666, 23598, 29450, 36330, 44352, 53636, 64308, 76500, 90350, 106002, 123606, 143318, 165300, 189720, 216752, 246576, 279378, 315350, 354690, 397602, 444296
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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a(n) = 1*2*3 + 2*3*4 + 3*4*5 +. . .+ (n-2)*(n-1)*n +(n-1)*n*1+ n*1*2, the sum of the cyclic product of terms taken three at a time, final term being n*1*2=2n.
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LINKS
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Harry J. Smith, Table of n, a(n) for n=0,...,1000
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EXAMPLE
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a(4) = 1*2*3 + 2*3*4 + 3*4*1 + 4*1*2 = 50.
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PROGRAM
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(PARI) { for (n=0, 1000, write("b062026.txt", n, " ", n*(n + 1)*(n^2 - 3*n + 6)/4) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 29 2009]
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CROSSREFS
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Equals 2 * A004255.
Sequence in context: A002529 A018027 A059413 this_sequence A048495 A089380 A081154
Adjacent sequences: A062023 A062024 A062025 this_sequence A062027 A062028 A062029
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jun 02 2001
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EXTENSIONS
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More terms from Larry Reeves (larryr(AT)acm.org), Jun 06 2001
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