A095386 Largest prime factor of peak values of 3x+1 trajectory started at n.

2, 2, 2, 2, 2, 13, 2, 13, 2, 13, 2, 5, 13, 5, 2, 13, 13, 11, 5, 2, 13, 5, 3, 11, 5, 577, 13, 11, 5, 577, 2, 5, 13, 5, 13, 7, 11, 19, 5, 577, 2, 7, 13, 17, 5, 577, 3, 37, 11, 29, 13, 5, 577, 577, 7, 7, 11, 19, 5, 23, 577, 577, 2, 7, 5, 19, 17, 13, 5, 577, 3, 577, 7, 17, 11, 29, 19, 101, 5

Offset: 2

Author

Labos Elemer, Jun 14 2004

Keywords

• nonn

Examples

			n=27: peak = 9232 = 2*2*2*2*577, so a(27)=577;
more extensive search suggests that all primes may occur as largest prime factor of peak.
		

Crossrefs

Cf. A006530, A025586.

Formula

a(n) = A006530(A025586(n)).