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Primitive numbers n such that the product of factorials of all proper divisors of n does not divide n!.
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%I #13 Aug 05 2017 14:35:09

%S 24,30,36,40,54,84,100,102,112,126,132,140,156,176,198,208,220,228,

%T 234,260,272,276,294,308,340,342,348,350,364,372,380,392,414,444,460,

%U 462,476,490,492,516,522,532,546,558,564,572,580,608,620,636,644,666,708

%N Primitive numbers n such that the product of factorials of all proper divisors of n does not divide n!.

%C If a number is in the sequence, all of its multiples also meet the criterion, but are not included. This is what the word "primitive" refers to.

%F a(n) appears to be asymptotic to c*n with 12 < c < 15. - _Benoit Cloitre_, Sep 16 2002

%e The product of the factorials of the proper divisors of 24, 1! * 2! * 3! * 4! * 6! * 8! * 12!, is divisible by 2^26 and therefore does not divide 24! (which is divisible by 2^22 only). 24 is the smallest number with this property. - _M. F. Hasler_, Dec 31 2016

%t f[n_] := n!/Apply[Times, Drop[Divisors[n], -1]! ]; a = {}; Do[b = f[n]; If[ !IntegerQ[b], If[ Select[n/a, IntegerQ] == {}, a = Append[a, n]]], {n, 1, 725}]; a

%Y Cf. A075071. See A075460 for the odd terms of this sequence.

%Y See A248693 for the list of all (also non-primitive) terms (and PARI code).

%K nonn

%O 1,1

%A _Robert G. Wilson v_ & _Amarnath Murthy_, Sep 14 2002

%E Edited by _M. F. Hasler_, Dec 30 2016