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 A091012 #3 Mar 30 2012 18:50:43 %S A091012 6,15,28,40,91,153,190,220,325,496,544,561,572,627,703,861,897,935, %T A091012 946,1012,1225,1287,1292,1431,1581,1610,1653,1768,1891,2278,2300,2465, %U A091012 2618,2701,2967,3321,3344,3496,3596,3655,3952,4123,4301,4324,4371 %N A091012 Numbers having exactly one divisor d such that for some x also d-x and d+x are divisors. %C A091012 A091009(a(n)) = 1. %Y A091012 Cf. A091013, A091011. %K A091012 nonn %O A091012 1,1 %A A091012 _Reinhard Zumkeller_, Dec 13 2003