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 A086558 #5 Dec 05 2013 19:56:20 %S A086558 1,23,307,4489,50021,600007,7000003,80062991,900660121,1000000006, %T A086558 11000000021,120000000004,1300000000021,14000000000001, %U A086558 150000000000017,1604502443050081,17000000000000009,180000000000000027 %N A086558 Smallest n-digit number beginning with n and having prime signature of n, or 0 if no such number exists. %C A086558 Conjecture: no term is zero. %e A086558 a(4) = 4489 = 67^2, 4= 2^2. a(12) = 120000000004= 2^2*30000000001, prime signature: p^2*q. %K A086558 base,nonn %O A086558 1,2 %A A086558 _Amarnath Murthy_, Aug 30 2003 %E A086558 Corrected and extended by _Sascha Kurz_, Sep 22 2003