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A072510 Numbers n with property that n = product of first k divisors of n for some k. 4

%I #16 May 20 2017 21:27:27

%S 1,2,3,5,6,7,8,10,11,13,14,15,17,19,21,22,23,24,26,27,29,30,31,33,34,

%T 35,37,38,39,40,41,43,46,47,51,53,55,56,57,58,59,61,62,64,65,67,69,70,

%U 71,73,74,77,79,82,83,85,86,87,89,91,93,94,95,97,101,103,105,106,107

%N Numbers n with property that n = product of first k divisors of n for some k.

%C Contains all prime numbers, numbers with two different prime factors... First 37 terms are the same as that of A036537. 54 is member of A036537, but it is not member of this sequence. 64 is member of this sequence but not of A036537. - _Vladimir Baltic_, Aug 03 2002

%H Harvey P. Dale, <a href="/A072510/b072510.txt">Table of n, a(n) for n = 1..10000</a>

%e 8 is a member as 8 = 1*2*4. but 9 is not as the divisors of 9 are 1,3,9 and 9 is not a partial product.

%t Select[Range[110],MemberQ[FoldList[Times,1,Divisors[#]],#]&] (* _Harvey P. Dale_, Jan 01 2014 *)

%o (PARI) isok(n) = {d = divisors(n); pr = 1; for(k=1, #d, pr *= d[k]; if (pr == n, return(1)););} \\ _Michel Marcus_, May 19 2017

%K nonn

%O 1,2

%A _Amarnath Murthy_, Jul 22 2002

%E More terms from _Vladimir Baltic_, Aug 03 2002

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Last modified April 24 18:17 EDT 2024. Contains 371962 sequences. (Running on oeis4.)