A247872 Least prime factor of A247681(n).

5, 7, 5, 7, 5, 11, 17, 5, 7, 19, 5, 11, 7, 5, 13, 5, 11, 23, 5, 19, 7, 5, 13, 7, 5, 17, 5, 7, 13, 5, 23, 7, 5, 29, 17, 5, 11, 13, 5, 31, 7, 37, 19, 5, 11, 7, 5, 17, 5, 7, 11, 5, 29, 7, 5, 17, 11, 5, 31, 23, 41, 5, 13, 7, 5, 19, 7, 5, 13, 5, 7, 5, 23, 7, 5, 19, 11, 31, 5, 5, 7, 11, 5, 37, 7, 5, 47, 53, 11, 5, 7, 43, 13, 5, 7

Offset: 2

Author

Odimar Fabeny, Sep 25 2014

Keywords

• nonn
• easy

Links

• Odimar Fabeny, Table of n, a(n) for n = 2..10000

Crossrefs

Cf. A056608, A247681.

Programs

Maple

count:= 0:
for n from 1 while count < 100 do
   m:= 1+18*n;
   if not isprime(m) then
      count:= count+1;
      A[count]:= min(numtheory:-factorset(m))
   fi
od:
seq(A[i],i=1..count); # Robert Israel, Sep 30 2014