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 A106473 #8 Sep 08 2012 14:43:01
%S A106473 1,11,121,1111,12321,111111,1214121,11311311,121252121,1111111111,
%T A106473 12341614321,111111111111,1212127212121,11315311351311,
%U A106473 121412181214121,1111111111111111,12321612921612321,111111111111111111
%N A106473 Rows of A003989 expressed as base 10 numbers.
%C A106473 The all-1 entries occur at positions indexed by the n-th primes-2 (A040976). The 1's then sum to give n-th prime-1 (A006093). The sum of the digits of a(n) is given by A006579(n+1).
%F A106473 a(n) = sum{k=0..n, GCD(n-k+1, k+1)*10^k}.
%K A106473 easy,nonn,base
%O A106473 0,2
%A A106473 _Paul Barry_, May 03 2005