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A139294 2^(2p - 1), where p is a Mersenne prime A000668(n). 19

%I

%S 32,8192,2305843009213693952,

%T 14474011154664524427946373126085988481658748083205070504932198000989141204992

%N 2^(2p - 1), where p is a Mersenne prime A000668(n).

%C Next terms have 4932, 78913, 315652, 1292913986, and 1388255822130839283 decimal digits. - _Jens Kruse Andersen_, Jul 14 2014

%F a(n) = 2^(2*A000668(n)-1).

%t A000668 := Select[2^Range[500] - 1, PrimeQ]; Table[2^(2*A000668[[n]] - 1), {n, 1, 5}] (* _G. C. Greubel_, Oct 03 2017 *)

%o (PARI) \p 100

%o print1("a(n): "); forprime(q=2, 7, p=2^q-1; if(isprime(p), print1(2^(2*p-1)", ")));

%o print1("\nNumber of digits in a(n): "); forprime(q=2, 127, p=2^q-1; if(isprime(p), print1(ceil((2*p-1)*log(2)/log(10))", "))) \\ _Jens Kruse Andersen_, Jul 14 2014

%Y Cf. A000079, A000668, A139286, A139295, A139296, A139297, A139298, A139299, A139300, A139301, A139302, A139303, A139304, A139305, A139306.

%K nonn

%O 1,1

%A _Omar E. Pol_, Apr 13 2008

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Last modified March 24 19:33 EDT 2019. Contains 321448 sequences. (Running on oeis4.)