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A246107
Number of inequivalent n X n matrices with entries from [n], where equivalence means permutations of rows or columns.
3
1, 1, 7, 738, 7880456, 20834113243925, 19909522361922032493690, 10114980502439545115146468340980932, 3861175753082201291221743022346066208381644388448, 1493197587365241166689220567691206411606485768307602552950789523519
OFFSET
0,3
FORMULA
a(n) = A246106(2n,n).
MAPLE
b:= proc(n, i) option remember; `if`(n=0, [[]],
`if`(i<1, [], [b(n, i-1)[], seq(map(p->[p[], [i, j]],
b(n-i*j, i-1))[], j=1..n/i)]))
end:
A:= proc(n, k) option remember; add(add(k^add(add(i[2]*j[2]*
igcd(i[1], j[1]), j=t), i=s) /mul(i[1]^i[2]*i[2]!, i=s)
/mul(i[1]^i[2]*i[2]!, i=t), t=b(n$2)), s=b(n$2))
end:
a:= n-> A(n$2):
seq(a(n), n=0..12);
CROSSREFS
Main diagonal of A246106.
Sequence in context: A249834 A064571 A111476 * A156618 A027685 A248385
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 13 2014
STATUS
approved