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 A278054 Primes p of the form sigma(2^(q+1)) for some prime q. 2
 31, 127, 8191, 524287, 2147483647, 2305843009213693951 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The next term is too large to include (see the table). Corresponding values of primes q are in A278053. Subsequence of Mersenne primes (A000668). LINKS Jaroslav Krizek, Table of n, a(n) for n = 1..7 EXAMPLE 8191 = sigma(2^(q+1)) for prime q = 11. MATHEMATICA Select[DivisorSigma[1, 2^(# + 1)] & /@ Prime@ Range@ 120, PrimeQ] (* Michael De Vlieger, Nov 10 2016 *) PROG (MAGMA) [SumOfDivisors(2^(n+1)): n in [1..1000] | IsPrime(n) and IsPrime(SumOfDivisors(2^(n+1)))] CROSSREFS Cf. A000043, A000203, A153798, A278053. Sequence in context: A079141 A049203 A065403 * A035502 A259509 A183838 Adjacent sequences:  A278051 A278052 A278053 * A278055 A278056 A278057 KEYWORD nonn AUTHOR Jaroslav Krizek, Nov 09 2016 STATUS approved

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Last modified April 16 18:53 EDT 2021. Contains 343050 sequences. (Running on oeis4.)