This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A238751 #25 Nov 07 2024 22:00:14
%S A238751 11,251,1019,4091,65531,4294967291
%N A238751 Lesser prime of third Mersenne prime pair {2^m - 5, 5*2^m - 1}.
%C A238751 By comparing A059608 and A001770, the next term, if it exists, is larger than 2^350028. - _Giovanni Resta_, Mar 06 2014
%C A238751 Lesser prime of Mersenne prime pair of order k and of the form {2^m - (2k - 1), (2k - 1)*2^m - 1}:
%C A238751 for order k = 1: 3, 7, 31, 127, 8191, 131071, ... (Mersenne primes A000668)
%C A238751 for order k = 2: 5, 13, 61, ...
%C A238751 for order k = 3: 11, 251, 1019, 4091, 655531, 4294967291, ... (this sequence)
%C A238751 for order k = 4:
%C A238751 for order k = 5: 2097143, ...
%C A238751 for order k = 6: 3, ...
%C A238751 for order k = 7:
%C A238751 for order k = 8: 17, 1009, 16369, ...
%C A238751 for order k = 9: 47, 65519, 1048559, 68719476719, ...
%C A238751 for order k = 10: 13, 2097133, ...
%C A238751 for order k = 11: 107, 8171, ...
%C A238751 for order k = 12: 41, 233, 4073, ...
%C A238751 for order k = 13: 487, ...
%C A238751 for order k = 14: 5, 229, 997, ...
%C A238751 for order k = 15: 97, ...
%F A238751 Numbers 2^m - 5 for m belonging to the intersection of A001770 and A059608. - _Max Alekseyev_, Feb 20 2024
%e A238751 11 is in this sequence because Mersenne prime pair {2^4-(2*3-1) = 11, (2*3-1)*2^4-1 = 79} where 3 is order and 11 is lesser prime (for m = 4).
%t A238751 2^Select[Range[1000], PrimeQ[2^# - 5] && PrimeQ[5*2^# - 1] &] - 5 (* _Giovanni Resta_, Mar 06 2014 *)
%Y A238751 Cf. A237422, A238694, A238749, A059608, A001770, A156560, A050522.
%K A238751 nonn,more
%O A238751 1,1
%A A238751 _Ilya Lopatin_ and _Juri-Stepan Gerasimov_, Mar 04 2014