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A062965
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Positive numbers which are one less than a perfect square that is also another power.
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1
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15, 63, 80, 255, 624, 728, 1023, 1295, 2400, 4095, 6560, 9999, 14640, 15624, 16383, 20735, 28560, 38415, 46655, 50624, 59048, 65535, 83520, 104975, 117648, 130320, 159999, 194480, 234255, 262143, 279840, 331775, 390624, 456975, 531440, 614655
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| W. Dunham, Euler: The Master of Us All, The Mathematical Association of America, Washington D.C., 1999, p. 65.
L. Euler, "Variae observationes circa series infinitas," Opera Omnia, Ser. 1, Vol. 14, pp. 216-244.
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LINKS
| L. Euler, Variae observationes circa series infinitas
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EXAMPLE
| a(2)=63 because the perfect square 64= 8^2 = 4^3.
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MATHEMATICA
| Table[ Denominator[ Plus@@(Take[ Select[ Range[ 2, 150 ], GCD@@(Last/@FactorInteger[ # ])>1& ]^2-1, k ]^-1) ], {k, 1, 16} ]
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CROSSREFS
| Cf. A037450, A062834, A062757, A001597.
Sequence in context: A067572 A066584 A065915 * A157968 A141759 A104473
Adjacent sequences: A062962 A062963 A062964 * A062966 A062967 A062968
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KEYWORD
| nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Jul 16 2001
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EXTENSIONS
| More terms from Dean Hickerson (dean.hickerson(AT)yahoo.com), Jul 24, 2001
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