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 A133278 #18 Nov 09 2013 02:58:55 %S A133278 2,3,5,5,11,17,7,19,31,43 %N A133278 Triangle read by rows, with n-th row the smallest non-constant n-term arithmetic progression of primes beginning with prime(n). %H A133278 <a href="/index/Pri#primes_AP">Index entries for sequences related to primes in arithmetic progressions</a> %e A133278 Triangle begins: %e A133278 2 %e A133278 3 5 %e A133278 5 11 17 %e A133278 7 19 31 43 %Y A133278 Cf. A231406. %K A133278 nonn,tabl %O A133278 1,1 %A A133278 _N. J. A. Sloane_, Oct 17 2007 %E A133278 Sequence corrected by _Jonathan Sondow_, Nov 08 2013