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 A090000 #9 Apr 25 2019 03:36:31
%S A090000 1,2,1,3,2,2,1,2,3,3,5,1,1,2,4,2,3,4,2,3,1,4,2,2,2,2,3,2,2,3,7,2,1,2,
%T A090000 1,3,3,2,3,2,2,2,6,2,2,3,2,5,3,3,3,4,4,5,1,3,2,4,1,2,2,1,2,3,3,4,2,1,
%U A090000 2,3,2,3,4,3,4,7,2,2,2,2,2,2,4,2,3,3,3,3,3,4,3,5,4,4,5,5,7,1,2,3,2,2,2,3,3
%N A090000 Length of longest contiguous block of 1's in binary expansion of n-th prime.
%C A090000 a(n) = A038374(A000040(n)).
%H A090000 John Mason, <a href="/A090000/b090000.txt">Table of n, a(n) for n = 1..20000</a>
%t A090000 f[n_] := Length[ Union[ DeleteCases[ Split[ IntegerDigits[n, 2]], 0, 2]][[ -1]]]; Table[ f[ Prime[n]], {n, 1, 105}] (* _Robert G. Wilson v_, Dec 04 2003 *)
%Y A090000 Cf. A000120, A004676, A090001, A090002, A090003, A090046, A090593.
%K A090000 nonn,base
%O A090000 1,2
%A A090000 _Reinhard Zumkeller_, Nov 20 2003