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A113937
Powerful(1) pentagonal numbers: intersection of A001694 and A000326.
0
1, 9801, 16008300, 94109401, 34346991901, 270990840125, 903638458801, 8676736387298001, 83314021887196947001, 124808911896093027867000, 799981229484128697805801, 37807513098010134416714700, 138451237954843775785881876, 7681419682192581869134354401
OFFSET
1,2
COMMENTS
a(15) > 10^28. - Donovan Johnson, Jun 28 2011
FORMULA
Solutions to the Diophantine equation b^2*c^3 = d(3d-1)/2. [Charles R Greathouse IV, Jun 28 2011]
EXAMPLE
94109401=7921*(3*7921-1)/2 is the 7921st pentagonal number and 94109401=89^2*109^2.
CROSSREFS
Sequence in context: A156735 A227489 A350918 * A036353 A174769 A031597
KEYWORD
nonn
AUTHOR
Giovanni Resta, Jan 31 2006
EXTENSIONS
a(8) from Donovan Johnson, Dec 07 2008
a(9) from Donovan Johnson, Jun 20 2011
a(10)-a(14) from Donovan Johnson, Jun 28 2011
STATUS
approved