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 A087341 #10 Feb 28 2021 09:53:32 %S A087341 89,138140141,87889091,8890919293,141516182021,122123124125126128129, %T A087341 121122123124125126128129,707274757677788081,21222425262728303233, %U A087341 206207208209210212213214215216217,405406407408410411412413414415416417 %N A087341 Smallest prime which is a concatenation of n successive composite numbers. %C A087341 a(3) contains three digit composite numbers as every concatenation of two digit numbers n,n+2 and n+3 is == 0 (mod 7). %H A087341 G. L. Honaker, Jr. and Chris Caldwell, <a href="https://primes.utm.edu/curios/page.php?short=138140141">Prime Curios! 138140141</a>. %H A087341 G. L. Honaker, Jr. and Chris Caldwell, <a href="https://primes.utm.edu/curios/page.php?short=87889091">Prime Curios! 87889091</a>. %e A087341 a(2) = 89 is the concatenation of two successive composite numbers 8 and 9. %e A087341 a(3) = 138140141 is the concatenation of 138,140 and 141. %Y A087341 Cf. A002808. %K A087341 base,nonn %O A087341 2,1 %A A087341 _Amarnath Murthy_, Sep 06 2003 %E A087341 More terms from _David Wasserman_, May 10 2005