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A066903 Primes in A006577.

%I A066903 #14 Mar 26 2019 06:48:10
%S A066903 7,2,5,3,19,17,17,7,7,23,5,13,13,109,29,11,11,11,19,19,19,19,107,107,
%T A066903 17,17,17,17,113,113,113,7,41,41,103,103,23,23,23,23,23,23,23,67,31,
%U A066903 31,31,31,31,31,13,13,13,13,101,101,13,13,127,83,127,47,47,109,47,109,109
%N A066903 Primes in A006577.
%H A066903 Robert Israel, <a href="/A066903/b066903.txt">Table of n, a(n) for n = 1..10000</a>
%e A066903 a(1) = 7 because the first prime in A006577 is A006577(3) = 7.
%p A066903 N:= 1000; # to get the first N terms
%p A066903 Collatz:= proc(n) option remember;
%p A066903 if n::even then 1+Collatz(n/2)
%p A066903 else 1+Collatz(3*n+1)
%p A066903 fi
%p A066903 end proc;
%p A066903 Collatz(1):= 0;
%p A066903 count:= 0;
%p A066903 for i from 1 while count < N do
%p A066903   x:= Collatz(i);
%p A066903   if isprime(x) then count:= count+1; A[count]:= x fi;
%p A066903 od:
%p A066903 seq(A[i],i=1..N); # _Robert Israel_, Jun 01 2014
%t A066903 M = 100;
%t A066903 Collatz[n_] := Collatz[n] = If[EvenQ[n], 1+Collatz[n/2], 1+Collatz[3n+1]];
%t A066903 Collatz[1] = 0;
%t A066903 count = 0;
%t A066903 For[i = 1, count < M, i++, x = Collatz[i]; If[PrimeQ[x], count = count+1; a[count] = x]];
%t A066903 Array[a, M] (* _Jean-François Alcover_, Mar 26 2019, after _Robert Israel_ *)
%Y A066903 Cf. A006577.
%K A066903 nonn,look
%O A066903 1,1
%A A066903 K. B. Subramaniam (kb_subramaniambalu(AT)yahoo.com), Dec 20 2001
%E A066903 More terms from _Sascha Kurz_, Mar 23 2002
%E A066903 Offset corrected by _Robert Israel_, Jun 01 2014