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 A172199 #30 Aug 06 2014 16:27:47 %S A172199 10,90,900,9000,74667,608673 %N A172199 Number of numbers with 2n+1 digits that are lunar squares. %C A172199 Every lunar square (see A087019) has an odd number of digits. Lunar squares with <= 7 digits are all distinct, but for longer numbers there are many examples of pairs of numbers whose lunar squares coincide. %H A172199 D. Applegate, M. LeBrun and N. J. A. Sloane, <a href="http://arxiv.org/abs/1107.1130">Dismal Arithmetic</a> [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing] %H A172199 <a href="/index/Di#dismal">Index entries for sequences related to dismal (or lunar) arithmetic</a> %Y A172199 Cf. A087019, A180513, A181319. %K A172199 nonn,base,more %O A172199 1,1 %A A172199 _David Applegate_, _Marc LeBrun_ and _N. J. A. Sloane_, Jan 20 2011