A190808 Increasing sequence generated by these rules: a(1)=1, and if x is in a then 2x and 3x+1 are in a.

1, 2, 4, 7, 8, 13, 14, 16, 22, 25, 26, 28, 32, 40, 43, 44, 49, 50, 52, 56, 64, 67, 76, 79, 80, 85, 86, 88, 97, 98, 100, 104, 112, 121, 128, 130, 133, 134, 148, 151, 152, 157, 158, 160, 169, 170, 172, 176, 193, 194, 196, 200, 202, 208, 224, 229, 238, 241, 242, 256

Offset

1,2

Comments

See A190803.

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Mathematica

h = 2; i = 0; j = 3; k = 1; f = 1; g = 9 ;
a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]  (* A190808 *)
b = a/2; c = (a - 1)/3; r = Range[1, 900];
d = Intersection[b, r] (* A190851 *)
e = Intersection[c, r] (* A190852 *)

Prog

(Haskell)
import Data.Set (singleton, deleteFindMin, insert)
a190808 n = a190808_list !! (n-1)
a190808_list = f $ singleton 1
   where f s = m : (f $ insert (2*m) $ insert (3*m+1) s')
             where (m, s') = deleteFindMin s
-- Reinhard Zumkeller, Jun 01 2011

Crossrefs

Cf. A190803, A190851, A190852.

Sequence in context: A236217 A320628 A260488 * A359727 A018614 A176745

Adjacent sequences: A190805 A190806 A190807 * A190809 A190810 A190811

Keyword

nonn

Author

Clark Kimberling, May 20 2011

Extensions

a(55)=224 inserted by Reinhard Zumkeller, Jun 01 2011

Status

approved