A200810 Iterate k -> d(k) until an odd prime is reached.

3, 3, 5, 3, 7, 3, 3, 3, 11, 3, 13, 3, 3, 5, 17, 3, 19, 3, 3, 3, 23, 3, 3, 3, 3, 3, 29, 3, 31, 3, 3, 3, 3, 3, 37, 3, 3, 3, 41, 3, 43, 3, 3, 3, 47, 3, 3, 3, 3, 3, 53, 3, 3, 3, 3, 3, 59, 3, 61, 3, 3, 7, 3, 3, 67, 3, 3, 3, 71, 3, 73, 3, 3, 3, 3, 3, 79, 3, 5, 3, 83

Offset

3,1

Comments

Csajbók and Kasza call this "lasttau(n)". Imre Kátai asks for its asymptotic behavior.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 3..10000

Tímea Csajbók and János Kasza, Iterating the tau-function, Annales Univ. Sci. Budapest., Sec. Math. 35 (2011), pp. 83-93.

Prog

(PARI) a(n)=while(!isprime(n), n=numdiv(n)); n \\ Charles R Greathouse IV, Nov 23 2011

Crossrefs

Cf. A200811, A200815.

Sequence in context: A015971 A163167 A243729 * A365710 A114003 A219792

Adjacent sequences: A200807 A200808 A200809 * A200811 A200812 A200813

Keyword

nonn

Author

Charles R Greathouse IV, Nov 23 2011

Status

approved