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 A068195 #11 Apr 06 2020 12:34:28 %S A068195 1,3,6,10,28,136,496,8128,32896,33550336,2147516416,8589869056, %T A068195 137438691328,2305843008139952128, %U A068195 2658455991569831744654692615953842176 %N A068195 Numbers of the form n(n+1)/2 whose only representation as a sum of 2 or more consecutive positive integers is 1+2+...+n. %C A068195 Consists of 1, even perfect numbers and numbers of the form n(n+1)/2 where n+1 is a Fermat prime. (See A068194 for proof.) %H A068195 Jon Perry, <a href="https://web.archive.org/web/20060515222746/http://www.users.globalnet.co.uk/~perry/maths/erdosmoser/erdosmoser.htm">Erdos-Moser</a> %Y A068195 Cf. A000396, A000668, A019434, A068194. %Y A068195 Record values in A082184. %K A068195 nonn %O A068195 1,2 %A A068195 _Jon Perry_, Feb 19 2002 %E A068195 Edited by _Dean Hickerson_, Feb 22 2002