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 A225300 #31 Apr 14 2021 05:27:24 %S A225300 1,9,27,20457529,87463589042698969 %N A225300 Terms in A025475 that are palindromes in base 2. %e A225300 9 = 1001_2. %e A225300 27 = 11011_2. %e A225300 20457529 = 1001110000010100000111001_2. %Y A225300 Intersection of A006995 and A025475. %Y A225300 Cf. A029983. %K A225300 nonn,base,more %O A225300 1,2 %A A225300 _Alex Ratushnyak_, May 04 2013 %E A225300 Definition clarified by _Chai Wah Wu_, Mar 18 2018