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 A113918 #13 Feb 03 2015 21:12:23
%S A113918 2,18,2,3050,34762,3087549,2
%N A113918 Cardinality of Image^inf({ 2 }) under repeated base-n zero-split squaring.
%C A113918 Define f_b(x) to be the set of base b numbers left after splitting x^2 at its zero digits and Image_b(S) = union_{x in S}{ { x } union f_b(S) }, then a(n) = | Image_n^inf({ 2 }) |.
%C A113918 Conjecture: a(n) is finite for all n.
%H A113918 Hugo van der Sanden, <a href="https://github.com/hvds/seq/tree/master/zerofree">Perl and C implementations</a>, Feb 03 2015
%e A113918 f_10(29648) = { 4, 39, 879 } since 29648^2 = 879003904.
%e A113918 a(8) = 2 since Image_8({ 2 }) = { 2, 4 } and f_8({ 2, 4 }) = { 2, 4 } and |{ 2, 4 }| is 2.
%Y A113918 Cf. A113917.
%K A113918 nonn,hard
%O A113918 2,1
%A A113918 _Hugo van der Sanden_ extending a suggestion from _David W. Wilson_, Jan 31 2006
%E A113918 Corrected by _Hugo van der Sanden_, Feb 03 2015