A054575 - OEIS

%I #10 Sep 07 2019 08:13:32

%S 4,2,2,2,3,2,2,2,2,2,5,2,10,2,3,3,2,3,3,3,3,2,2,2,2,4,2,3,3,3,2,3,3,2,

%T 2,6,18,2,2,2,16,3,16,4,2,2,4,3,2,4,2,2,5,3,2,3,2,3,4,6,3,2,12,10,2,2,

%U 4,2,4,2,2,10,2,4,3,2,4,2,3,2,2,9,6,2,2,20,3,2,3,3,3,2,10,15,2,2,11,10

%N Number of iterations to reach new prime in A054574.

%H Amiram Eldar, <a href="/A054575/b054575.txt">Table of n, a(n) for n = 1..10000</a>

%e a(5)=3 because beginning at 11, the next prime, 47, is attained in 3 steps.

%t f[n_] := n + Plus @@ Times @@@ FactorInteger@n; a[n_] := Length[NestWhileList[f, (p = Prime[n]), # == p || CompositeQ[#] &]] - 1; Array[a, 100] (* _Amiram Eldar_, Sep 07 2019 *)

%Y Cf. A054574.

%K easy,nonn

%O 1,1

%A _Enoch Haga_, Apr 11 2000