A050779 - OEIS

%I #9 Oct 17 2019 22:41:32

%S 2,3,5,7,13,37,43,61,67,73,97,101,137,139,157,163,173,181,193,197,199,

%T 211,223,233,257,277,281,283,307,347,349,353,367,379,389,397,409,421,

%U 433,457,463,487,499,547,557,563,577,601,613,617,641,643,661,673,677

%N Primes that are not ending primes after the iterated procedure of 'composite added to the sum of its prime factors reaches a prime'.

%t a[n_]:=NestWhile[#+Total[Times@@@FactorInteger[#]]&,n,!PrimeQ[#]&]; t={}; Do[If[!PrimeQ[n],AppendTo[t,a[n]]],{n,4,nn=678}]; Complement[Prime[Range[PrimePi[nn]]],Select[Union[t],#<nn&]] (* _Jayanta Basu_, Jun 01 2013 *)

%Y Cf. A050778, A050703-A050710.

%K nonn

%O 1,1

%A _Patrick De Geest_, Sep 15 1999