A096861 Function A062401(x) = phi(sigma(x)) = f(x) is iterated. Starting with n, a(n) is the largest term arising in trajectory.

1, 2, 3, 6, 5, 6, 7, 8, 12, 10, 11, 12, 13, 14, 15, 30, 17, 30, 19, 20, 30, 22, 23, 30, 30, 26, 30, 30, 29, 30, 31, 96, 33, 34, 35, 96, 37, 38, 39, 40, 41, 96, 43, 44, 45, 46, 47, 60, 96, 60, 51, 96, 53, 96, 55, 96, 96, 58, 59, 60, 61, 96, 63, 126, 65, 66, 96, 96, 96, 70, 71, 96

Offset: 1

Author

Labos Elemer, Jul 21 2004

Keywords

• nonn

Examples

			n=255: list={255,144,360,288,[432,480],432,...}, a(255)=480, a recurrent term;
n=247: list={247,96,72,96,...}, a(247)=247, a transient term, here the initial value.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384

Crossrefs

Cf. A000010, A000203, A062401, A062402, A095955, A096859, A096865.

Cf. also A096864.

Programs

Mathematica

gf[x_] :=DivisorSigma[1, EulerPhi[x]] itef[x_, len_] :=NestList[fs, x, len] Table[Max[itef[w, 20]], {w, 1, 256}]

Scheme

(define (A096861 n) (let loop ((visited (list n)) (m n)) (let ((next (A062401 (car visited)))) (cond ((member next visited) m) (else (loop (cons next visited) (max m next))))))) ;; Antti Karttunen, Nov 18 2017