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A072512
Product of all n - d, where 1 < d < n and d is a divisor of n.
1
1, 1, 1, 2, 1, 12, 1, 24, 6, 40, 1, 4320, 1, 84, 120, 1344, 1, 25920, 1, 43200, 252, 220, 1, 31933440, 20, 312, 432, 183456, 1, 136080000, 1, 322560, 660, 544, 840, 12563527680, 1, 684, 936, 919296000, 1, 1155772800, 1, 1219680, 1814400, 1012, 1
OFFSET
1,4
COMMENTS
If n is prime then a(n) = 1.
If n is not a prime or the square of a prime then n divides a(n).
EXAMPLE
For n = 16 the nontrivial divisors d are 2,4 and 8, so a(16) = (16-2)*(16-4)*(16-8) = 14*12*8 = 1344.
PROG
(PARI) for(n=1, 47, d=divisors(n); print1(prod(j=2, matsize(d)[2]-1, n-d[j]), ", "))
CROSSREFS
Cf. A072513.
Sequence in context: A163088 A105608 A051190 * A271531 A118588 A259633
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Jul 28 2002
EXTENSIONS
Edited and extended by Klaus Brockhaus, Jul 31 2002
STATUS
approved