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A075502
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Triangle read by rows: Stirling2 triangle with scaled diagonals (powers of 7).
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10
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1, 7, 1, 49, 21, 1, 343, 343, 42, 1, 2401, 5145, 1225, 70, 1, 16807, 74431, 30870, 3185, 105, 1, 117649, 1058841, 722701, 120050, 6860, 147, 1, 823543, 14941423, 16235562, 4084101, 360150, 13034, 196, 1
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OFFSET
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1,2
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COMMENTS
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This is a lower triangular infinite matrix of the Jabotinsky type. See the D. E. Knuth reference given in A039692 for exponential convolution arrays.
The row polynomials p(n,x) := Sum_{m=1..n} a(n,m)x^m, n >= 1, have e.g.f. J(x; z)= exp((exp(7*z) - 1)*x/7) - 1.
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LINKS
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FORMULA
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a(n, m) = (7^(n-m)) * stirling2(n, m).
a(n, m) = 7*m*a(n-1, m) + a(n-1, m-1), n>=m>=1, else 0, with a(n, 0) := 0 and a(1, 1)=1.
a(n, m) = (Sum_{p=0..m-1} A075513(m, p)*((p+1)*7)^(n-m))/(m-1)! for n >= m >= 1, else 0.
G.f. for m-th column: (x^m)/Product_{k=1..m}(1-7*k*x), m >= 1.
E.g.f. for m-th column: (((exp(7*x)-1)/7)^m)/m!, m >= 1.
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EXAMPLE
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[1]; [7,1]; [49,21,1]; ...; p(3,x) = x * (49 + 21*x + x^2).
Triangle starts
* 1
* 7 1
* 49 21 1
* 343 343 42 1
* 2401 5145 1225 70 1
* 16807 74431 30870 3185 105 1
* 117649 1058841 722701 120050 6860 147 1
* 823543 14941423 16235562 4084101 360150 13034 196 1
(End)
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MATHEMATICA
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Flatten[Table[7^(n - m) StirlingS2[n, m], {n, 11}, {m, n}]] (* Indranil Ghosh, Mar 25 2017 *)
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PROG
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(PARI) for(n=1, 11, for(m=1, n, print1(7^(n - m) * stirling(n, m, 2), ", "); ); print(); ) \\ Indranil Ghosh, Mar 25 2017
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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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