# Echoes of ONU Research - Greatest Prime Factor Sequences

There are 5 entries devoted to our "greatest prime factor sequences" in *The Online Encyclopedia of Integer Sequences* (OEIS). The entries have been communicated by Neil Sloane, Technology Leader at AT&T Research Labs.

http://oeis.org/A006530 Gpf(n): greatest prime dividing n (with a(1)=1).

http://oeis.org/A175723 a(1)=a(2)=1; thereafter a(n) = gpf(a(n-1)+a(n-2))

http://oeis.org/A177904 a(1)=a(2)=a(3)=1; thereafter a(n) = gpf(a(n-1)+a(n-2)+a(n-3))

http://oeis.org/A177923 a(1)=19, a(2)=13, a(3)=37; thereafter a(n)=gpf(a(n-1)+a(n-2)+a(n-3))

http://oeis.org/A178174 a(1)=a(2)=a(3)=a(4)=1; thereafter a(n)=gpf(a(n-1)+a(n-2)+a(n-3)+a(n-4))

The sequences introduced in the paper * The Greatest Prime Factor and Recurrent Sequences* (Fibonacci Quarterly 48, no. 4, 358-362) by

**Greg Back**(ONU '10) and

**Dr. Mihai Caragiu**(Professor of Mathematics) have been one of the topics discussed in

*Rutgers University's Experimental Mathematics Seminar*