A191132 Increasing sequence generated by these rules: a(1)=1, and if x is in a then 3x+1 and 4x-3 are in a.

1, 4, 13, 40, 49, 121, 148, 157, 193, 364, 445, 472, 481, 580, 589, 625, 769, 1093, 1336, 1417, 1444, 1453, 1741, 1768, 1777, 1876, 1885, 1921, 2308, 2317, 2353, 2497, 3073, 3280, 4009, 4252, 4333, 4360, 4369, 5224, 5305, 5332, 5341, 5629, 5656, 5665, 5764, 5773, 5809, 6925, 6952, 6961, 7060, 7069, 7105, 7492, 7501

Offset

1,2

Comments

See A191113.

Links

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

Mathematica

h = 3; i = 1; j = 4; k = -3; f = 1; g = 9;
a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]   (* A191132 *)
b = (a - 1)/3; c = (a + 3)/4; r = Range[1, 2500];
d = Intersection[b, r] (* A191188 *)
e = Intersection[c, r] (* A191189 *)

Prog

(Haskell)
import Data.Set (singleton, deleteFindMin, insert)
a191132 n = a191132_list !! (n-1)
a191132_list = 1 : f (singleton 4)
   where f s = m : (f $ insert (3*m+1) $ insert (4*m-3) s')
             where (m, s') = deleteFindMin s
-- Reinhard Zumkeller, Jun 01 2011

Crossrefs

Cf. A191113.

Sequence in context: A271012 A272581 A342159 * A360606 A119915 A307577

Adjacent sequences: A191129 A191130 A191131 * A191133 A191134 A191135

Keyword

nonn

Author

Clark Kimberling, May 27 2011

Status

approved