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A121360 Smallest k such that A002217(k)=n. 1

%I

%S 2,1,8,14,26,62,134,393,1257,4659,9314,27933,167073,334142,4677862,

%T 14033577,56134292,2133102298,11788191218,52541651594

%N Smallest k such that A002217(k)=n.

%C Least number which becomes prime or 0 or 4 after n-1 iterations of f(x) = sum of prime factors of x (cf. A001414). Agrees with A048133 except for the second term.

%C a(21) <= 536226160966. a(22) <= 2681130804805. a(23) <= 8512643845707. - Donovan Johnson

%Y Cf. A002217, A001414, A048133.

%K nonn

%O 1,1

%A _Klaus Brockhaus_, Jul 27 2006

%E Edited comment and a(19)-a(20) from _Donovan Johnson_, Oct 16 2010

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Last modified June 20 00:47 EDT 2019. Contains 324223 sequences. (Running on oeis4.)