A273340 - OEIS

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.

%I #5 May 21 2016 22:53:35

%S 2,17,145,577,5185

%N 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 (PARI) composite(n) = my(i=0, c=2); while(1, if(!ispseudoprime(c), i++); if(i==n, return(c)); c++)

%o a273339(n) = forcomposite(c=1, , if(Mod(n, c^2)^(c-1)!=1, return(c)))

%o a(n) = my(b=2, c=composite(n)); while(a273339(b)!=c, b++); b

%Y Cf. A273339.

%K nonn,more

%O 1,1

%A _Felix Fröhlich_, May 20 2016