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 A115293 Row sums of correlation triangle for (1+x)^3/(1-x). 1
 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; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS 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 Janjic, Oct 28 2007 LINKS Milan Janjic, Two Enumerative Functions Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA 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)}}. MATHEMATICA LinearRecurrence[{3, -3, 1}, {1, 8, 31, 80, 160, 272}, 50] (* Harvey P. Dale, Dec 03 2018 *) CROSSREFS Sequence in context: A302874 A061294 A240707 * A212579 A115004 A303522 Adjacent sequences:  A115290 A115291 A115292 * A115294 A115295 A115296 KEYWORD easy,nonn AUTHOR Paul Barry, Jan 19 2006 STATUS approved

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Last modified March 29 21:32 EDT 2020. Contains 333117 sequences. (Running on oeis4.)