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 A261801 Number of 9-compositions of n: matrices with 9 rows of nonnegative integers with positive column sums and total element sum n. 2
 1, 9, 126, 1704, 22986, 310086, 4183260, 56435004, 761346207, 10271072557, 138563678736, 1869317246556, 25218347263608, 340212470558832, 4589695110222504, 61918074814238448, 835316485437693186, 11268981358631127288, 152026139882340589466 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Also the number of compositions of n where each part i is marked with a word of length i over a nonary alphabet whose letters appear in alphabetical order. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..880 FORMULA G.f.: (1-x)^9/(2*(1-x)^9-1). a(n) = A261780(n,9). a(n) = Sum_{k>=0} (1/2)^(k+1) * binomial(n-1+9*k,n). - Seiichi Manyama, Aug 06 2024 MAPLE a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*binomial(j+8, 8), j=1..n)) end: seq(a(n), n=0..20); CROSSREFS Column k=9 of A261780. Sequence in context: A261743 A229283 A144073 * A065086 A246238 A234573 Adjacent sequences: A261798 A261799 A261800 * A261802 A261803 A261804 KEYWORD nonn,easy,changed AUTHOR Alois P. Heinz, Sep 01 2015 STATUS approved

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Last modified August 14 03:23 EDT 2024. Contains 375146 sequences. (Running on oeis4.)