A176112 Primes that take a prime number of steps to reach 1 under the Collatz function.

3, 5, 41, 43, 53, 61, 109, 139, 149, 163, 167, 173, 179, 227, 233, 269, 307, 317, 373, 401, 439, 443, 479, 541, 557, 563, 607, 617, 619, 661, 751, 787, 827, 863, 911, 937, 1069, 1087, 1093, 1097, 1193, 1259, 1297, 1303, 1321, 1373, 1381, 1409, 1439

Offset

1,1

Comments

Primes p such that A006577(p) is prime. - Charles R Greathouse IV, May 12 2015

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Mathematica

pnsQ[n_]:=PrimeQ[Length[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&]]- 1];  Select[Prime[Range[500]], pnsQ] (* Harvey P. Dale, Nov 28 2016 *)

Prog

(PARI) A006577(n)=my(s); while(n>1, n=if(n%2, 3*n+1, n/2); s++); s
select(p->isprime(A006577(p)), primes(100)) \\ Charles R Greathouse IV, May 12 2015

Crossrefs

Cf. A006577.

Sequence in context: A300938 A183258 A077779 * A215133 A146318 A228968

Adjacent sequences: A176109 A176110 A176111 * A176113 A176114 A176115

Keyword

nonn

Author

Kent Edward Hays (hayske(AT)gmail.com), Apr 08 2010

Status

approved