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 A318593 Number of n-member subsets of [5*n] whose elements sum to a multiple of five. 2
 1, 1, 9, 91, 969, 10630, 118755, 1344904, 15380937, 177232627, 2054455670, 23930713170, 279871768995, 3284214703056, 38650751381832, 456002537343580, 5391644226101705, 63871405575418665, 757929628541719755, 9007607943130625829, 107196674080761940470 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..922 FORMULA a(n) = floor(A163456(n)) + [n mod 5 = 0]*A163455(n/5), with A163456(n) = binomial(5*n,n)/5 and A163455(n) = binomial(5*n-1,n) where [] is an Iverson bracket. - Georg Fischer, Mar 23 2019 EXAMPLE a(2) = 9: {1,4}, {1,9}, {2,3}, {2,8}, {3,7}, {4,6}, {5,10}, {6,9}, {7,8}. MAPLE b:= proc(n, s, m, t) option remember; `if`(n=0, `if`(s=0 and t=0, 1, 0),       b(n-1, s, m, t)+`if`(t=0, 0, b(n-1, irem(s+n, m), m, t-1)))     end: a:= n-> b(5*n, 0, 5, n): seq(a(n), n=0..27); CROSSREFS Column k=5 of A318557. Cf. A163455, A163456. Sequence in context: A242299 A109108 A163456 * A176735 A286786 A123792 Adjacent sequences:  A318590 A318591 A318592 * A318594 A318595 A318596 KEYWORD nonn AUTHOR Alois P. Heinz, Aug 29 2018 STATUS approved

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Last modified May 24 16:47 EDT 2019. Contains 323533 sequences. (Running on oeis4.)