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 A023568 #12 Sep 09 2017 11:54:53
%S A023568 0,0,1,1,1,2,2,1,2,2,2,2,2,2,2,2,2,2,1,2,3,2,2,2,2,2,2,2,2,3,2,1,2,2,
%T A023568 2,2,3,2,2,3,2,2,2,3,2,2,2,3,2,2,3,2,3,2,2,3,3,2,2,2,3,3,2,3,3,2,2,2,
%U A023568 2,2,3,2,3,3,2,3,2,2,2,3,2,3,2,3,2,3,2,2,2,3,2,3,2,2,2,2,3,3,3
%N A023568 Number of distinct prime divisors of prime(n)-3.
%C A023568 a(n) = 1 if prime(n) is in A057733. - _Robert Israel_, Dec 28 2015
%H A023568 Robert Israel, <a href="/A023568/b023568.txt">Table of n, a(n) for n = 1..10000</a>
%p A023568 0,0,seq(nops(numtheory:-factorset(ithprime(i)-3)), i=3..100); # _Robert Israel_, Dec 28 2015
%t A023568 Join[{0,0},PrimeNu/@(Prime[Range[3,100]]-3)] (* _Harvey P. Dale_, Sep 09 2017 *)
%Y A023568 Cf. A023569, A057733.
%K A023568 nonn
%O A023568 1,6
%A A023568 _Clark Kimberling_