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Search: id:A115293
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| A115293 |
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Row sums of correlation triangle for (1+x)^3/(1-x). |
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+0
2
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| 1, 8, 31, 80, 160, 272, 416, 592, 800, 1040, 1312, 1616, 1952, 2320, 2720, 3152, 3616, 4112, 4640, 5200, 5792, 6416, 7072, 7760, 8480, 9232, 10016, 10832, 11680, 12560, 13472, 14416, 15392, 16400, 17440, 18512, 19616, 20752, 21920, 23120, 24352
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row sums of number triangle A115292.
If Y_i (i=1,2,3,4,5) are 2-blocks of a (n+5)-set X then a(n-2) is the number of 7-subsets of X intersecting each Y_i (i=1,2,3,4,5). - Milan R. Janjic (agnus(AT)blic.net), Oct 28 2007
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LINKS
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Milan Janjic, Two Enumerative Functions
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FORMULA
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G.f.: (1+x)^5/(1-x)^3; a(n)=sum{k=0..n, sum{j=0..n, [j<=k]*A115291(k-j)*[j<=n-k]*A115291(n-k-j)}}.
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CROSSREFS
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Sequence in context: A067950 A022273 A061294 this_sequence A115004 A005338 A006322
Adjacent sequences: A115290 A115291 A115292 this_sequence A115294 A115295 A115296
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jan 19 2006
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