A079893 a(n) = gcd(n, A079892(n)), where A079892(n) is the least number > n having one more distinct prime factor than n.

1, 2, 3, 2, 1, 6, 1, 2, 1, 10, 1, 6, 1, 2, 15, 2, 1, 6, 1, 10, 3, 2, 1, 6, 1, 2, 1, 2, 1, 30, 1, 1, 3, 2, 7, 6, 1, 2, 3, 2, 1, 42, 1, 4, 15, 2, 1, 12, 1, 10, 3, 4, 1, 6, 5, 4, 3, 2, 1, 30, 1, 2, 3, 1, 1, 6, 1, 2, 1, 70, 1, 6, 1, 2, 3, 2, 1, 6, 1, 4, 1, 2, 1, 42, 5, 2, 3, 2, 1, 30, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2

Offset: 1

Author

Reinhard Zumkeller, Jan 14 2003

Keywords

• nonn
• look

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A079891, A079894.

Programs

PARI

A079893(n) = { my(x=1+omega(n)); for(k=1+n, oo, if(omega(k)==x, return(gcd(k,n)))); }; \\ Antti Karttunen, Mar 02 2023