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 A182156 Numbers k such that 2^k-61 is prime. 0

%I

%S 6,7,11,15,17,21,23,25,31,35,57,67,85,165,213,217,331,351,695,721,815,

%T 825,1007,1403,1725,1833

%N Numbers k such that 2^k-61 is prime.

%C For these k, N=2^(k-1)*(2^k-61) is of abundance A033880(N)=60.

%C The five smallest numbers of abundance 60 are 96, 126, 4288, 2034688, 535871488. Four out of these five are of the form 2^(k-1)*(2^k-61).

%o (PARI) for(k=1,999,ispseudoprime(2^k-61)&print1(k","))

%K nonn,more

%O 1,1

%A _M. F. Hasler_, Apr 14 2012

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Last modified December 7 00:16 EST 2019. Contains 329812 sequences. (Running on oeis4.)