A225748 Numbers n for which the sum of the numbers in the Collatz (3x+1) iteration of n is prime.

2, 4, 12, 16, 22, 38, 48, 52, 64, 66, 67, 90, 93, 132, 148, 149, 155, 163, 165, 185, 201, 208, 222, 229, 230, 237, 242, 264, 268, 275, 289, 309, 324, 332, 339, 351, 352, 359, 362, 363, 373, 382, 384, 401, 403, 465, 471, 474, 485, 507, 517, 518, 528, 532

Offset

1,1

Links

Table of n, a(n) for n=1..54.

Example

12 is a member since 12 + 6 + 3 + 10 + 5 + 16 + 8 + 4 + 2 + 1 = 67 is a prime.

Mathematica

coll[n_]:=NestWhileList[If[EvenQ[#], #/2, 3#+1] &, n, #>1 &]; Select[Range[500], PrimeQ[Total[coll[#]]] &]

Crossrefs

Cf. A033493.

Sequence in context: A230770 A224703 A171943 * A358231 A114064 A071118

Adjacent sequences: A225745 A225746 A225747 * A225749 A225750 A225751

Keyword

nonn

Author

Jayanta Basu, May 14 2013

Status

approved