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A245334
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A factorial-like triangle read by rows: T(0,0) = 1; T(n+1,0) = T(n,0)+1; T(n+1,k+1) = T(n,0)*T(n,k), k=0..n.
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25
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1, 2, 1, 3, 4, 2, 4, 9, 12, 6, 5, 16, 36, 48, 24, 6, 25, 80, 180, 240, 120, 7, 36, 150, 480, 1080, 1440, 720, 8, 49, 252, 1050, 3360, 7560, 10080, 5040, 9, 64, 392, 2016, 8400, 26880, 60480, 80640, 40320, 10, 81, 576, 3528, 18144, 75600, 241920, 544320
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OFFSET
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0,2
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COMMENTS
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row(0) = {1}; row(n+1) = row(n) multiplied by n and prepended with (n+1);
T(2*n,n) = A002690(n), central terms;
T(n,0) = n + 1;
T(n,n-10) = 11 * A051431(n-10), n > 9;
T(n,n-9) = 10 * A049398(n-9), n > 8;
T(n,n-8) = 9 * A049389(n-8), n > 7;
T(n,n-7) = 8 * A049388(n-7), n > 6;
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LINKS
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FORMULA
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EXAMPLE
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. 0: 1;
. 1: 2, 1;
. 2: 3, 4, 2;
. 3: 4, 9, 12, 6;
. 4: 5, 16, 36, 48, 24;
. 5: 6, 25, 80, 180, 240, 120;
. 6: 7, 36, 150, 480, 1080, 1440, 720;
. 7: 8, 49, 252, 1050, 3360, 7560, 10080, 5040;
. 8: 9, 64, 392, 2016, 8400, 26880, 60480, 80640, 40320;
. 9: 10, 81, 576, 3528, 18144, 75600, 241920, 544320, 725760, 362880.
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MATHEMATICA
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Table[(n!)/((n - k)!)*(n + 1 - k), {n, 0, 9}, {k, 0, n}] // Flatten (* Michael De Vlieger, Sep 10 2017 *)
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PROG
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(Haskell)
a245334 n k = a245334_tabl !! n !! k
a245334_row n = a245334_tabl !! n
a245334_tabl = iterate (\row@(h:_) -> (h + 1) : map (* h) row) [1]
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CROSSREFS
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Cf. A000142, A001715, A001720, A001725, A001730, A049388, A049389, A049398, A051431, A052849, A070960.
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KEYWORD
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AUTHOR
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STATUS
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approved
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