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 A116935 #8 Jun 15 2016 10:38:19
%S A116935 123,1234,1234567,
%T A116935 12345678910111213141516171819202122232425262728293031323334
%N A116935 Semiprimes (A001358) which are the concatenation of the numbers 1 through n for some n.
%C A116935 Next term has 185 digits, and it is thus too large to be included. It is equal to the concatenation of the first 97 integers. - _Giovanni Resta_, Jun 15 2016
%F A116935 {A007908} intersect {A001358}.
%e A116935 a(1) = 123 = 3 * 41.
%e A116935 a(2) = 1234 = 2 * 617.
%e A116935 a(3) = 1234567 = 127 * 9721.
%e A116935 a(4) = 2 * 6172839455055606570758085909601061116212631364146515661667.
%Y A116935 Cf. A001358, A007908.
%K A116935 base,nonn,less
%O A116935 1,1
%A A116935 _Jonathan Vos Post_, Mar 20 2006