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%I #8 May 01 2013 20:54:48
%S 5,12,70,210,11310,145860,1560090,23130030,2491434660,200736225690,
%T 1906748513670,281993526895080,9427390580377770,904832960818356570,
%U 117584828859645537390,2928413909631253063020,400579656276180828206760
%N Smallest pentagonal number with n distinct prime factors.
%C a(18) <= 44573764536301609937057730. - _Donovan Johnson_, Feb 15 2012
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PentagonalNumber.html">Pentagonal Numbers</a>.
%e a(9) = 2491434660 = 2^2*3*5*11*13*17*19*29*31. 2491434660 is the smallest pentagonal number with 9 distinct prime factors.
%Y Cf. A000326, A076551, A156237, A156238, A156239.
%K nonn
%O 1,1
%A _Donovan Johnson_, Feb 07 2009
%E a(17) from _Donovan Johnson_, Jun 26 2011
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