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A294746
Number A(n,k) of compositions (ordered partitions) of 1 into exactly k*n+1 powers of 1/(k+1); square array A(n,k), n>=0, k>=0, read by antidiagonals.
21
1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 10, 13, 1, 1, 1, 35, 217, 75, 1, 1, 1, 126, 4245, 8317, 525, 1, 1, 1, 462, 90376, 1239823, 487630, 4347, 1, 1, 1, 1716, 2019836, 216456376, 709097481, 40647178, 41245, 1, 1, 1, 6435, 46570140, 41175714454, 1303699790001, 701954099115, 4561368175, 441675, 1
OFFSET
0,9
COMMENTS
Row r >= 2, is asymptotic to r^(r*n + 3/2) / (2*Pi*n)^((r-1)/2). - Vaclav Kotesovec, Sep 20 2019
LINKS
FORMULA
A(n,k) = [x^((k+1)^n)] (Sum_{j=0..k*n+1} x^((k+1)^j))^(k*n+1) for k>0, A(n,0) = 1.
EXAMPLE
A(3,1) = 13: [1/4,1/4,1/4,1/4], [1/2,1/4,1/8,1/8], [1/2,1/8,1/4,1/8], [1/2,1/8,1/8,1/4], [1/4,1/2,1/8,1/8], [1/4,1/8,1/2,1/8], [1/4,1/8,1/8,1/2], [1/8,1/2,1/4,1/8], [1/8,1/2,1/8,1/4], [1/8,1/4,1/2,1/8], [1/8,1/4,1/8,1/2], [1/8,1/8,1/2,1/4], [1/8,1/8,1/4,1/2].
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, ...
1, 3, 10, 35, 126, 462, ...
1, 13, 217, 4245, 90376, 2019836, ...
1, 75, 8317, 1239823, 216456376, 41175714454, ...
1, 525, 487630, 709097481, 1303699790001, 2713420774885145, ...
MAPLE
b:= proc(n, r, p, k) option remember;
`if`(n<r, 0, `if`(r=0, `if`(n=0, p!, 0), add(
b(n-j, k*(r-j), p+j, k)/j!, j=0..min(n, r))))
end:
A:= (n, k)-> `if`(k=0, 1, b(k*n+1, 1, 0, k+1)):
seq(seq(A(n, d-n), n=0..d), d=0..10);
MATHEMATICA
b[n_, r_, p_, k_] := b[n, r, p, k] = If[n < r, 0, If[r == 0, If[n == 0, p!, 0], Sum[b[n - j, k*(r - j), p + j, k]/j!, {j, 0, Min[n, r]}]]];
A[n_, k_] := If[k == 0, 1, b[k*n + 1, 1, 0, k + 1]];
Table[A[n, d - n], {d, 0, 10}, {n, 0, d}] // Flatten (* Jean-François Alcover, Apr 30 2018, after Alois P. Heinz *)
CROSSREFS
Main diagonal gives: A294747.
Cf. A294775.
Sequence in context: A263383 A185620 A096066 * A326180 A064085 A256692
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Nov 07 2017
STATUS
approved