A190805 Increasing sequence generated by these rules: a(1)=1, and if x is in a then 2x-1 and 3x+1 are in a.

1, 4, 7, 13, 22, 25, 40, 43, 49, 67, 76, 79, 85, 97, 121, 130, 133, 148, 151, 157, 169, 193, 202, 229, 238, 241, 256, 259, 265, 292, 295, 301, 313, 337, 364, 385, 391, 400, 403, 445, 454, 457, 472, 475, 481, 508, 511, 517, 529, 580, 583, 589, 601, 607, 625, 673, 688, 715, 724, 727

Offset

1,2

Comments

See A190803.

Links

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

Mathematica

h = 2; i = -1; j = 3; k = 1; f = 1; g = 10 ;
a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]  (* A190805 *)
b = (a + 1)/2; c = (a - 1)/3; r = Range[1, 500];
d = Intersection[b, r] (* A190845 *)
e = Intersection[c, r] (* A190808 conjectured *)

Prog

(Haskell)
import Data.Set (singleton, deleteFindMin, insert)
a190805 n = a190805_list !! (n-1)
a190805_list = 1 : f (singleton 4)
   where f s = m : (f $ insert (2*m-1) $ insert (3*m+1) s')
             where (m, s') = deleteFindMin s
-- Reinhard Zumkeller, Jun 01 2011

Crossrefs

Cf. A190803, A190845.

Sequence in context: A068940 A147487 A190845 * A008471 A156622 A111314

Adjacent sequences: A190802 A190803 A190804 * A190806 A190807 A190808

Keyword

nonn

Author

Clark Kimberling, May 20 2011

Extensions

a(56)=673 inserted by Reinhard Zumkeller, Jun 01 2011

Status

approved