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 A197817 #10 May 09 2021 11:12:06 %S A197817 121,20,33,4141,55,6161,77,8051,9409,10201,1111,120269,1313,140209, %T A197817 150547,160229,1717,180457,1919,20002379,210367,220417,2323,240277, %U A197817 250247,260123,270187,280157,2929,301781,3131,32003357,330007,340973,350743,360761,3737,380053 %N A197817 Smallest composite m such that m and the smallest prime divisor of m begin with n. %C A197817 Except for the number 22, the sequence A176597 (double primes: concatenation of the n-th prime with itself) is a subsequence of this sequence. %e A197817 a(8) = 8051 = 83*97 => 8051 and 83 start with 8. %p A197817 with(numtheory): for n from 1 to 60 do: l1:=length(n):i:=0:for m from 2 to 32*10^6 while(i=0) do: x:=factorset(m):y:=x[1]: l2:=length(m):x1:=floor(m/(10^(l2-l1))): l3:=length(y):x2:=floor(y/(10^(l3-l1))):if x1=n and x2=n and l2>=l1 and l3 >=l1 and type(m,prime)=false then i:=1: printf ( "%d %d \n",n,m):else fi :od:od: %Y A197817 Cf. A176597, A197816. %K A197817 nonn,base %O A197817 1,1 %A A197817 _Michel Lagneau_, Oct 18 2011