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 A138875 #13 Mar 15 2020 04:07:48 %S A138875 66,2828,4996,8128,3336,8556,1328,2328,2676,1916,1328,1428,2376,1428, %T A138875 5428,1028,9976,3356,1836,4028,1116,5976,3936,9356,1076,8116,3656, %U A138875 1428,1328,1316,2728,1528,8336,8428,3316,1976,8156,9536,4256,7928,4428,7428,4956,7756,2028,1476,5016 %N A138875 Concatenation of first two digits and last two digits of n-th even perfect number. %H A138875 Jan Munch Pedersen, <a href="http://amicable.homepage.dk/perfect.htm">Known Perfect Numbers</a> [BROKEN LINK] %Y A138875 Cf. A000396, A104511, A138843, A138863, A138866, A138877. %K A138875 base,nonn %O A138875 1,1 %A A138875 _Omar E. Pol_, Apr 02 2008 %E A138875 More terms from http://amicable.homepage.dk/perfect.htm sent by Steven Bi (chenhsi(AT)stanford.edu), Dec 22 2008 %E A138875 More terms from same site sent by Steven Bi (chenhsi(AT)stanford.edu), Jan 09 2009 %E A138875 More terms from _Jinyuan Wang_, Mar 14 2020