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A181511
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Triangle T(n,k) = n!/(n-k)! read by rows, 0 <= k < n.
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4
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1, 1, 2, 1, 3, 6, 1, 4, 12, 24, 1, 5, 20, 60, 120, 1, 6, 30, 120, 360, 720, 1, 7, 42, 210, 840, 2520, 5040, 1, 8, 56, 336, 1680, 6720, 20160, 40320, 1, 9, 72, 504, 3024, 15120, 60480, 181440, 362880, 1, 10, 90, 720, 5040, 30240, 151200, 604800, 1814400, 3628800
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listen;
history;
text;
internal format)
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OFFSET
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1,3
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COMMENTS
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Row n contains the same set of values as row A181512(n,.), which are related to labeled rooted trees (A000169) and Bell numbers (A000110) respectively.
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LINKS
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FORMULA
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EXAMPLE
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The triangle begins:
1;
1, 2;
1, 3, 6;
1, 4, 12, 24;
which is A181512 without duplicates.
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MAPLE
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A181511 := proc(n, k) n!/(n-k)! ; end proc:
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PROG
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(Haskell)
a181511 n k = a181511_tabl !! (n-1) !! k
a181511_row n = a181511_tabl !! (n-1)
a181511_tabl = tail $ map init a008279_tabl
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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