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A013988
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Triangle read by rows, the inverse Bell transform of n!*binomial(5,n) (without column 0).
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11
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1, 5, 1, 55, 15, 1, 935, 295, 30, 1, 21505, 7425, 925, 50, 1, 623645, 229405, 32400, 2225, 75, 1, 21827575, 8423415, 1298605, 103600, 4550, 105, 1, 894930575, 358764175, 59069010, 5235405, 271950, 8330, 140, 1, 42061737025, 17398082625, 3016869625, 289426830, 16929255, 621810, 14070, 180, 1
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OFFSET
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1,2
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COMMENTS
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Previous name was: Triangle of numbers related to triangle A049224; generalization of Stirling numbers of second kind A008277, Bessel triangle A001497.
T(n, m) = S2p(-5; n,m), a member of a sequence of triangles including S2p(-1; n,m) = A001497(n-1,m-1) (Bessel triangle) and ((-1)^(n-m))*S2p(1; n,m) = A008277(n,m) (Stirling 2nd kind). T(n, 1) = A008543(n-1).
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LINKS
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FORMULA
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T(n, m) = n!*A049224(n, m)/(m!*6^(n-m));
T(n+1, m) = (6*n-m)*T(n, m) + T(n, m-1), for n >= m >= 1, with T(n, m) = 0, n<m, and T(n, 0) = 0, T(1, 1) = 1.
E.g.f. of m-th column: ((1 - (1-6*x)^(1/6))^m)/m!.
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EXAMPLE
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Triangle begins as:
1;
5, 1;
55, 15, 1;
935, 295, 30, 1;
21505, 7425, 925, 50, 1;
623645, 229405, 32400, 2225, 75, 1;
21827575, 8423415, 1298605, 103600, 4550, 105, 1;
894930575, 358764175, 59069010, 5235405, 271950, 8330, 140, 1;
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MATHEMATICA
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(* First program *)
rows = 10;
b[n_, m_] := BellY[n, m, Table[k! Binomial[5, k], {k, 0, rows}]];
A = Table[b[n, m], {n, 1, rows}, {m, 1, rows}] // Inverse // Abs;
(* Second program *)
T[n_, k_]:= T[n, k]= If[k==0, 0, If[k==n, 1, (6*(n-1) -k)*T[n-1, k] +T[n-1, k-1]]];
Table[T[n, k], {n, 12}, {k, n}]//Flatten (* G. C. Greubel, Oct 03 2023 *)
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PROG
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(Sage) # uses[inverse_bell_matrix from A264428]
# Adds 1, 0, 0, 0, ... as column 0 at the left side of the triangle.
inverse_bell_matrix(lambda n: factorial(n)*binomial(5, n), 8) # Peter Luschny, Jan 16 2016
(Magma)
if k eq 0 then return 0;
elif k eq n then return 1;
else return (6*(n-1)-k)*T(n-1, k) + T(n-1, k-1);
end if;
end function;
[T(n, k): k in [1..n], n in [1..12]]; // G. C. Greubel, Oct 03 2023
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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