A064921 - OEIS

%I #11 Jun 21 2018 02:01:38

%S 2,3,3,5,3,7,5,5,3,11,3,13,5,7,5,17,5,19,5,5,3,23,3,5,5,11,3,29,3,31,

%T 17,13,5,11,5,37,5,7,3,41,3,43,5,13,3,47,5,13,5,19,5,53,5,7,5,5,3,59,

%U 5,61,17,7,13,17,5,67,5,5,5,71,5,73,5,19,3,17,5,79,5,29,3,83,5,5,5,31,5

%N Iterate A064920 until a prime is reached.

%C Well defined since A064920(n) < n for nonprimes.

%C a(p) = p for all primes p.

%H Harry J. Smith, <a href="/A064921/b064921.txt">Table of n, a(n) for n = 2..1000</a>

%e a(18) = 5 as A064920(18) = 8 and A064920(8) = 5.

%o (PARI) gpf(n)= { local(f); f=factor(n)~; return(f[1, length(f)]) } { for (n=2, 1000, m=n; while (!isprime(m), g=gpf(m); m=m / g + g - 1); write("b064921.txt", n, " ", m) ) } \\ _Harry J. Smith_, Sep 29 2009

%Y Cf. A064920, A064922, A064917.

%K nonn

%O 2,1

%A _Reinhard Zumkeller_, Oct 14 2001