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 A096520 #5 Oct 15 2013 22:32:26
%S A096520 2,3,3,3,2,3,2,2,1,3,1,3,1,1,2,3,2,5,1,4,1,2,4,2,0,2,0,2,2,5,3,3,2,0,
%T A096520 0,3,2,2,3,2,2,3,1,4,0,2,2,1,0,2,1,2,1,1,2,2,4,1,0,1,4,0,2,2,0,3,3,2,
%U A096520 2,2,1,1,1,3,1,3,3,3,2,1,2,4,1,3,1,3,1,1,5,3,2,1,2,2,4,2,0,4,0,1,1,2,0,2,2
%N A096520 Number of primes in the neighborhood of center=2^n and radius=Ceiling[Log[2^n]].
%e A096520 First in the suitable neighborhood of 2^25 no primes occur: a[25]=0, while around 2^127 6 primes arise: a[127]=6.
%t A096520 t=Table[Count[Table[PrimeQ[2^n+i], {i, -Ceiling[Log[2^n]//N], Ceiling[Log[2^n]//N]}], True], {n, 1, 256}]
%Y A096520 Cf. A096509-A096523.
%K A096520 nonn
%O A096520 1,1
%A A096520 _Labos Elemer_, Jul 12 2004