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Search: id:A133049
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| 9, 49, 961, 16129, 67092481, 17179607041, 274876858369, 4611686014132420609, 5316911983139663487003542222693990401, 383123885216472214589586755549637256619304505646776321
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OFFSET
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1,1
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COMMENT
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Sum of last A000043(n) divisors of the n-th even perfect number. In other words; sum of divisors that are not powers of 2 of the n-th even perfect number, or sum of divisors that are multiples of the n-th Mersenne prime A000668(n) of the n-th even perfect number. See A139247 for more information.
See the structure of the divisors of perfect numbers in A135652, A135653, A135654 and A135655.
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LINKS
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O. E. Pol, Determinacion geometrica de los numeros primos y perfectos.
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FORMULA
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a(n) = A000668(n)^2
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EXAMPLE
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a(3)=961 because the 3rd Mersenne prime is 31 and 31^2=961.
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CROSSREFS
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Cf. A000290, A001248. Mersenne primes: A000668.
Cf. A000043, A000396, A135652, A135653, A135654, A135655, A138247.
Sequence in context: A135625 A115326 A069666 this_sequence A050632 A050638 A088064
Adjacent sequences: A133046 A133047 A133048 this_sequence A133050 A133051 A133052
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KEYWORD
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nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Oct 30 2007, Apr 23 2008
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EXTENSIONS
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More terms from Olaf Voss (richyfourtythree(AT)yahoo.com), Feb 13 2008
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