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 A139288 #6 Jun 21 2021 12:07:21
%S A139288 4,16,256,4096,1048576,16777216,4294967296,68719476736,17592186044416,
%T A139288 72057594037927936,1152921504606846976,4722366482869645213696,
%U A139288 1208925819614629174706176,19342813113834066795298816
%N A139288 2^(2p - 1)/2, where p is prime.
%F A139288 a(n)=A139286(n)/2.
%t A139288 Table[2^(2p-1)/2,{p,Prime[Range[20]]}] (* _Harvey P. Dale_, Jun 21 2021 *)
%Y A139288 Cf. A139286, A139287, A139289, A139290, A139291, A139292, A139293, A139294, A139306.
%K A139288 nonn
%O A139288 1,1
%A A139288 _Omar E. Pol_, Apr 13 2008
%E A139288 More terms from _Jon E. Schoenfield_, Jul 16 2010