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 A084972 #2 Mar 30 2012 17:30:55
%S A084972 1,2,3,4,7,12,20,35,57,102,182,323,585,1061,1943,3521,6606
%N A084972 When A058033 first reaches n.
%t A084972 Primorial[n_] := Product[Prime[i], {i, 1, n}]; f[n_] := Block[{k = 2, p = 1}, While[q = Floor[ Log[2, Primorial[k]]]; q - p != n, k++; p = q]; k - 1]; Table[ f[n], {n, 1, 17}]
%Y A084972 Cf. A058033.
%K A084972 nonn
%O A084972 1,2
%A A084972 _Robert G. Wilson v_, May 22 2003