cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A050779 Primes that are not ending primes after the iterated procedure of 'composite added to the sum of its prime factors reaches a prime'.

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%I A050779 #9 Oct 17 2019 22:41:32
%S A050779 2,3,5,7,13,37,43,61,67,73,97,101,137,139,157,163,173,181,193,197,199,
%T A050779 211,223,233,257,277,281,283,307,347,349,353,367,379,389,397,409,421,
%U A050779 433,457,463,487,499,547,557,563,577,601,613,617,641,643,661,673,677
%N A050779 Primes that are not ending primes after the iterated procedure of 'composite added to the sum of its prime factors reaches a prime'.
%t A050779 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 A050779 Cf. A050778, A050703-A050710.
%K A050779 nonn
%O A050779 1,1
%A A050779 _Patrick De Geest_, Sep 15 1999