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 A137922 #8 May 13 2013 01:48:46 %S A137922 3,4,5,6,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83, %T A137922 89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173, %U A137922 179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281 %N A137922 Numbers having exactly two divisors d such that d+1 is not a divisor. %C A137922 A137921(a(n)) = 2; %C A137922 a(n) = A000040(n-1) for n > 4. %o A137922 (PARI) a(n)=if(n>4,prime(n-1),[3,4,5,6][n]) \\ _Charles R Greathouse IV_, Aug 21 2011 %K A137922 nonn,easy %O A137922 1,1 %A A137922 _Reinhard Zumkeller_, Feb 23 2008 %E A137922 Corrected by _Charles R Greathouse IV_, Apr 19 2010