A066903 Primes in A006577.

7, 2, 5, 3, 19, 17, 17, 7, 7, 23, 5, 13, 13, 109, 29, 11, 11, 11, 19, 19, 19, 19, 107, 107, 17, 17, 17, 17, 113, 113, 113, 7, 41, 41, 103, 103, 23, 23, 23, 23, 23, 23, 23, 67, 31, 31, 31, 31, 31, 31, 13, 13, 13, 13, 101, 101, 13, 13, 127, 83, 127, 47, 47, 109, 47, 109, 109

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(1) = 7 because the first prime in A006577 is A006577(3) = 7.

Maple

N:= 1000; # to get the first N terms
Collatz:= proc(n) option remember;
if n::even then 1+Collatz(n/2)
else 1+Collatz(3*n+1)
fi
end proc;
Collatz(1):= 0;
count:= 0;
for i from 1 while count < N do
  x:= Collatz(i);
  if isprime(x) then count:= count+1; A[count]:= x fi;
od:
seq(A[i], i=1..N); # Robert Israel, Jun 01 2014

Mathematica

M = 100;
Collatz[n_] := Collatz[n] = If[EvenQ[n], 1+Collatz[n/2], 1+Collatz[3n+1]];
Collatz[1] = 0;
count = 0;
For[i = 1, count < M, i++, x = Collatz[i]; If[PrimeQ[x], count = count+1; a[count] = x]];
Array[a, M] (* Jean-François Alcover, Mar 26 2019, after Robert Israel *)

Crossrefs

Cf. A006577.

Sequence in context: A372913 A366599 A352890 * A194886 A196764 A074457

Adjacent sequences: A066900 A066901 A066902 * A066904 A066905 A066906

Keyword

nonn,look

Author

K. B. Subramaniam (kb_subramaniambalu(AT)yahoo.com), Dec 20 2001

Extensions

More terms from Sascha Kurz, Mar 23 2002

Offset corrected by Robert Israel, Jun 01 2014

Status

approved