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%I #8 Mar 12 2015 19:17:45
%S 35,247,1247,2501,4187,15251,17767,33227,49051,63551,68587,71177,
%T 76501,81317,96647,112477,118301,128627,147737,159251,182527,241001,
%U 250717,265651,302177,318551,438751,485357,563347,655051,1563151,1600117
%N Pentagonal numbers (A000326) that are also brilliant numbers (A078972).
%C This is to pentagonal numbers A000326 as A113940 is to triangular numbers A000217. These may be seen as the 5th and 3rd row of an infinite array of k-gonal numbers which are also brilliant numbers, where the 4th row is A001248 squares of primes. - _Jonathan Vos Post_, Apr 05 2009
%F A000326 INTERSECTION A078972.
%e a(1) = 35 = 5th pentagonal number = 5*(3*5-1)/2 = 5 * 7, with the two prime factors each being one digit in length. a(2) = 247 = 13th pentagonal number = 13*(3*13-1)/2 = 13 * 19, with the two prime factors each being two digits in length. a(6) = 15251 = 101 * 151, with the two prime factors each being three digits in length. - _Jonathan Vos Post_, Apr 05 2009
%e 17767 is the 109th pentagonal number and 17767=109*163 is brilliant.
%Y Cf. A000326, A078972, A159190.
%Y Cf. A001222, A001248, A001358, A113940, A114439.
%K base,nonn
%O 1,1
%A _Giovanni Resta_, Jan 31 2006
%E Edited by _N. J. A. Sloane_, Apr 07 2009 at the suggestion of R. J. Mathar
%E Two more terms from _R. J. Mathar_, Apr 06 2009