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A133049
Squares of Mersenne primes A000668(n).
15
9, 49, 961, 16129, 67092481, 17179607041, 274876858369, 4611686014132420609, 5316911983139663487003542222693990401, 383123885216472214589586755549637256619304505646776321
OFFSET
1,1
COMMENTS
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.
FORMULA
a(n) = A000668(n)^2
EXAMPLE
a(3)=961 because the 3rd Mersenne prime is 31 and 31^2=961.
MATHEMATICA
Select[2^Range[1000] - 1, PrimeQ]^2 (* G. C. Greubel, Oct 03 2017 *)
PROG
(PARI) forprime(p=2, 1000, if(ispseudoprime(2^p-1), print1((2^p-1)^2", "))) \\ G. C. Greubel, Oct 03 2017
CROSSREFS
Cf. A000290, A001248. Mersenne primes: A000668.
Sequence in context: A069666 A175734 A174744 * A188140 A050632 A050638
KEYWORD
nonn
AUTHOR
Omar E. Pol, Oct 30 2007, Apr 23 2008
EXTENSIONS
More terms from Olaf Voß, Feb 13 2008
STATUS
approved