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 A098391 #5 Mar 20 2022 23:19:30 %S A098391 0,0,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, %T A098391 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3, %U A098391 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3 %N A098391 a(n) = Log2(Log2(prime(n))), where Log2 = A000523. %C A098391 a(n) = A000523(A098388(n)). %C A098391 a(n) = A000523(A000523(A000040(n))). %Y A098391 Cf. A000040, A000523, A098388. %K A098391 nonn %O A098391 1,7 %A A098391 _Reinhard Zumkeller_, Sep 06 2004