A078767 Let f(n) = A003434(n) be the number of iterations of phi needed to reach 1. Then a(n) = max(f(1), f(2), ..., f(n)).

0, 1, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7

Offset: 1

Author

Jon Perry, Jan 09 2003

Keywords

• easy
• nonn

Crossrefs

Cf. A003434.

Programs

PARI

epr(m,c)=if (c>0,m=eulerphi(m); c--; epr(m,c),m) x=1; for (n=1,100, while (epr(n,x)>1, x++); print1(x","))

Extensions

Description corrected by Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 31 2003