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 A034307 #14 Aug 11 2024 14:41:30 %S A034307 2,5,9,12,18,20,30,34 %N A034307 Numbers n such that there are no oblong (promic) palindromes of length n. %H A034307 P. De Geest, <a href="https://www.worldofnumbers.com/consec.htm">Palindromic pronic numbers of the form n(n+1)</a> %Y A034307 Cf. A002378, A028336, A028337. %K A034307 nonn,base,hard %O A034307 1,1 %A A034307 _Patrick De Geest_, Oct 15 1998