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 A111355 #10 Mar 30 2012 18:36:50
%S A111355 2,4,222,154,754,204,14,246,1300,3642
%N A111355 Consider the sequence defined in A083952 as a binary string of the digits 1 and 2. Then a(n) is the beginning position of the first occurrence of exactly 2n-1 consecutive 2's.
%C A111355 Strings of ones are always isolated and at an odd position.
%t A111355 a[0] = 1; a[l_] := a[l] = Block[{k = 1, s = Sum[ a[i]*x^i, {i, 0, l - 1}]}, While[ IntegerQ[ Last[ CoefficientList[ Series[(s + k*x^l)^(1/2), {x, 0, l}], x]]] != True, k++ ]; k]; p = Flatten[ Position[ Table[ a[n], {n, 0, 4150}], 1]]; f[n_] := Block[{k = n, m = 1}, While[m < Length[p] && p[[m + 1]] - p[[m]] != n, m++ ]; If[m < Length[p] - k, p[[m]] + 1, 0]]; Table[ f[2n], {n, 10}]
%Y A111355 Cf. A083952.
%K A111355 nonn
%O A111355 1,1
%A A111355 _Paul D. Hanna_ and _Robert G. Wilson v_, Nov 08 2005