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 A053559 #10 Sep 14 2018 04:59:44 %S A053559 23,67,89,131132133134135136137138139140141 %N A053559 Primes formed by concatenating n consecutive increasing numbers starting with a palindrome and ending with the next consecutive palindrome. %C A053559 The next term, a(5) = 90809...90909, has 505 digits. - _M. F. Hasler_, Sep 11 2018 %o A053559 (PARI) P=1; until(, N=P; for(x=1+P, P=A262038(1+P), N=N*10^(logint(x, 10)+1)+x); ispseudoprime(N)&& print(N",")) \\ _M. F. Hasler_, Sep 11 2018 %Y A053559 Cf. A000040, A002113. %K A053559 base,nonn %O A053559 1,1 %A A053559 _G. L. Honaker, Jr._, Jan 16 2000