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A113937
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Powerful(1) pentagonal numbers: intersection of A001694 and A000326.
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0
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1, 9801, 16008300, 94109401, 34346991901, 270990840125, 903638458801, 8676736387298001, 83314021887196947001, 124808911896093027867000, 799981229484128697805801, 37807513098010134416714700, 138451237954843775785881876, 7681419682192581869134354401
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(15) > 10^28. - Donovan Johnson, Jun 28 2011
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FORMULA
| Solutions to the Diophantine equation b^2*c^3 = d(3d-1)/2. [Charles R Greathouse IV, Jun 28 2011]
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EXAMPLE
| 94109401=7921*(3*7921-1)/2 is the 7921st pentagonal number and 94109401=89^2*109^2.
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CROSSREFS
| Cf. A001694, A000326.
Sequence in context: A035911 A069333 A156735 * A036353 A174769 A031687
Adjacent sequences: A113934 A113935 A113936 * A113938 A113939 A113940
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KEYWORD
| nonn
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AUTHOR
| Giovanni Resta (g.resta(AT)iit.cnr.it), Jan 31 2006
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EXTENSIONS
| a(8) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Dec 07 2008
a(9) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jun 20 2011
a(10)-a(14) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jun 28 2011
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