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%I #11 May 13 2013 01:48:37
%S 1,9801,16008300,94109401,34346991901,270990840125,903638458801,
%T 8676736387298001,83314021887196947001,124808911896093027867000,
%U 799981229484128697805801,37807513098010134416714700,138451237954843775785881876,7681419682192581869134354401
%N Powerful(1) pentagonal numbers: intersection of A001694 and A000326.
%C a(15) > 10^28. - Donovan Johnson, Jun 28 2011
%F Solutions to the Diophantine equation b^2*c^3 = d(3d-1)/2. [_Charles R Greathouse IV_, Jun 28 2011]
%e 94109401=7921*(3*7921-1)/2 is the 7921st pentagonal number and 94109401=89^2*109^2.
%Y Cf. A001694, A000326.
%K nonn
%O 1,2
%A _Giovanni Resta_, Jan 31 2006
%E a(8) from _Donovan Johnson_, Dec 07 2008
%E a(9) from _Donovan Johnson_, Jun 20 2011
%E a(10)-a(14) from _Donovan Johnson_, Jun 28 2011
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