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 A050874 #7 Aug 20 2021 16:53:08 %S A050874 38,42,52,56,70,78,82,90,100,108,112,120,134,138,140,143,146,148,151, %T A050874 158,162,168,171,174,176,179,182,186,196,200,205,206,208,213,214,220, %U A050874 224,233,234,236,241,242,244,248,262,266,268 %N A050874 Binary numbers d(1)...d(j) such that d(i) = d(j+1-i) for all but 6 values of i. %C A050874 Each number becomes a palindrome by changing three digits. %H A050874 Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a234/A234007.java">Java program</a> (github) %Y A050874 Cf. A051244, A051247. %K A050874 nonn,base %O A050874 1,1 %A A050874 _Clark Kimberling_ %E A050874 Name corrected by _Sean A. Irvine_, Aug 20 2021