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URL: https://oeis.org/A389590

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A389590
a(n) is the permanent of the Vandermonde matrix of the divisors of n.
1
1, 3, 4, 74, 6, 16272, 8, 57520, 426, 158680, 12, 5930052968448, 14, 764848, 729720, 5715121152, 18, 550668343903776, 20, 1423211174784000, 3386712, 6680080, 24, 40960969469666276724436893696, 4430, 15040792, 10986840, 62973187111747584, 30, 3643964867209811449098816000000
OFFSET
1,2
FORMULA
a(p) = p + 1 for prime p.
MAPLE
a:= n-> LinearAlgebra[Permanent]((l-> Matrix(nops(l), (i, j)
->(l[i])^(j-1)))(sort([numtheory[divisors](n)[]]))):
seq(a(n), n=1..30); # Alois P. Heinz, Oct 09 2025
MATHEMATICA
a[n_]:=Permanent[Table[Part[Divisors[n], i]^(j-1), {i, DivisorSigma[0, n]}, {j, DivisorSigma[0, n]}]]; Array[a, 30]
PROG
(PARI) a(n) = my(d=divisors(n)); matpermanent(matrix(#d, #d, i, j, d[i]^(j-1))); \\ Michel Marcus, Oct 09 2025
CROSSREFS
KEYWORD
nonn
AUTHOR
Stefano Spezia, Oct 08 2025
STATUS
approved