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A046060
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5-multiperfect numbers.
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20
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14182439040, 31998395520, 518666803200, 13661860101120, 30823866178560, 740344994887680, 796928461056000, 212517062615531520, 69357059049509038080, 87934476737668055040, 170206605192656148480
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OFFSET
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1,1
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COMMENTS
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Conjectured finite and probably these are the only terms; cf. Flammenkamp's link. [Georgi Guninski, Jul 25 2012]
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..65 (complete sequence from Flammenkamp)
F. Firoozbakht, M. F. Hasler, Variations on Euclid's formula for Perfect Numbers, JIS 13 (2010) #10.3.1
Achim Flammenkamp, The Multiply Perfect Numbers Page
Fred Helenius, Link to Glossary and Lists
Walter Nissen, Abundancy : Some Resources
Eric Weisstein's World of Mathematics, Multiperfect Number.
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EXAMPLE
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From Daniel Forgues, May 09 2010: (Start)
14182439040 = 2^7*3^4*5*7*11^2*17*19
sigma(14182439040) = (2^8-1)/1*(3^5-1)/2*(5^2-1)/4*(7^2-1)/6*(11^3-1)/10*(17^2-1)/16*(19^2-1)/18
= (255)*(121)*(6)*(8)*(133)*(18)*(20)
= (3*5*17)*(11^2)*(2*3)*(2^3)*(7*19)*(2*3^2)*(2^2*5)
= 2^7*3^4*5^2*7*11^2*17*19
= (5) * (2^7*3^4*5*7*11^2*17*19)
= 5 * 14182439040 (End)
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PROG
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(PARI) is(n)=sigma(n)==5*n \\ Charles R Greathouse IV, Apr 05 2013
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CROSSREFS
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Cf. A000396, A005820, A027687, A046061, A007539.
Sequence in context: A017616 A304234 A134298 * A172595 A172617 A216015
Adjacent sequences: A046057 A046058 A046059 * A046061 A046062 A046063
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KEYWORD
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nonn
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AUTHOR
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Eric W. Weisstein
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STATUS
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approved
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