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 A304431 #4 May 12 2018 17:21:38
%S A304431 0,1,1,1,3,3,3,3,3,4,4,4,4,7,7,7,7,7,7,9,9,9,9,9,9,9,9,10,13,13,13,13,
%T A304431 13,13,13,13,13,13,13,13,19,19,19,19,19,19,19,19,19,19,19,19,19,19,19,
%U A304431 21,21,22,27,27,27,27,27,27,27,27,27,27,27,27,27,27
%N A304431 a(n+1) = 1 + min( 2*a(floor(n/2)), 3*a(floor(n/3)) ), with a(0) = 0.
%C A304431 Same recursion as Knuth numbers A007448 but different initial value.
%o A304431 (PARI) {a(n) = if( n<1, 0, n--; 1 + min( a(n\2)*2, a(n\3)*3 ))};
%Y A304431 Cf. A007448.
%K A304431 nonn
%O A304431 0,5
%A A304431 _Michael Somos_, May 12 2018