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A196879
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Square array A(n,k), n>=0, k>=0, read by antidiagonals: A(n,k) is the number of partitions of n^k into powers of k.
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20
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 3, 10, 1, 1, 1, 1, 6, 23, 36, 1, 1, 1, 1, 9, 72, 132, 94, 1, 1, 1, 1, 16, 335, 1086, 729, 284, 1, 1, 1, 1, 36, 2220, 15265, 15076, 3987, 692, 1, 1, 1, 1, 85, 19166, 374160, 642457, 182832, 18687, 1828, 1, 1
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OFFSET
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0,13
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LINKS
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FORMULA
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For k>1: A(n,k) = [x^(n^k)] 1/Product_{j>=0}(1-x^(k^j)).
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EXAMPLE
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A(2,3) = 3, because the number of partitions of 2^3=8 into powers of 3 is 3: [1,1,3,3], [1,1,1,1,1,3], [1,1,1,1,1,1,1,1].
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, ...
1, 1, 4, 3, 6, 9, ...
1, 1, 10, 23, 72, 335, ...
1, 1, 36, 132, 1086, 15265, ...
1, 1, 94, 729, 15076, 642457, ...
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MAPLE
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b:= proc(n, j, k) local nn, r;
if n<0 then 0
elif j=0 then 1
elif j=1 then n+1
elif n<j then b(n, j, k):= b(n-1, j, k) +b(k*n, j-1, k)
else nn:= 1 +floor(n);
r:= n-nn;
(nn-j) *binomial(nn, j) *add(binomial(j, h)
/(nn-j+h) *b(j-h+r, j, k) *(-1)^h, h=0..j-1)
fi
end:
A:= proc(n, k) local s, t;
if k<2 then return 1 fi;
s:= floor(n^k/k);
t:= ilog[k](k*s+1);
b(s/k^(t-1), t, k)
end:
seq(seq(A(n, d-n), n=0..d), d=0..15);
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MATHEMATICA
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a[_, 0] = a[_, 1] = a[0, _] = a[1, _] = 1; a[n_, k_] := SeriesCoefficient[ 1/Product[ (1 - x^(k^j)), {j, 0, n}], {x, 0, n^k}]; Table[a[n - k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Dec 09 2013 *)
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CROSSREFS
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Columns k=0+1, 2-10 give: A000012, A196880, A196881, A196882, A196883, A196884, A196885, A196886, A196887, A196888.
Rows n=0+1, 2-10 give: A000012, A196889, A196890, A196891, A196892, A196893, A196894, A196895, A196896, A196897.
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KEYWORD
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AUTHOR
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STATUS
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approved
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