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 A273340 #5 May 21 2016 22:53:35 %S A273340 2,17,145,577,5185 %N A273340 Smallest base b such that A273339(b) = A002808(n), i.e., smallest base b > 1 such that the n-th composite number is the smallest "non-Wieferich pseudoprime" to base b. %o A273340 (PARI) composite(n) = my(i=0, c=2); while(1, if(!ispseudoprime(c), i++); if(i==n, return(c)); c++) %o A273340 a273339(n) = forcomposite(c=1, , if(Mod(n, c^2)^(c-1)!=1, return(c))) %o A273340 a(n) = my(b=2, c=composite(n)); while(a273339(b)!=c, b++); b %Y A273340 Cf. A273339. %K A273340 nonn,more %O A273340 1,1 %A A273340 _Felix Fröhlich_, May 20 2016