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A191128 Increasing sequence generated by these rules:  a(1)=1, and if x is in a then 3x and 4x-1 are in a. 5
1, 3, 9, 11, 27, 33, 35, 43, 81, 99, 105, 107, 129, 131, 139, 171, 243, 297, 315, 321, 323, 387, 393, 395, 417, 419, 427, 513, 515, 523, 555, 683, 729, 891, 945, 963, 969, 971, 1161, 1179, 1185, 1187, 1251, 1257, 1259, 1281, 1283, 1291, 1539, 1545, 1547, 1569, 1571, 1579, 1665, 1667, 1675, 1707, 2049, 2051, 2059, 2091, 2187 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A191113.

LINKS

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

MATHEMATICA

h = 3; i = 0; j = 4; k = -1; f = 1; g = 9;

a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]  (* A191128 *)

b = a/3; c = (a + 1)/4; r = Range[1, 1500];

d = Intersection[b, r] (* A191180 *)

e = Intersection[c, r] (* A191181 *)

m = (a + 1)/2  (* divisibility property *)

PROG

(Haskell)

import Data.Set (singleton, deleteFindMin, insert)

a191128 n = a191128_list !! (n-1)

a191128_list = f $ singleton 1

   where f s = m : (f $ insert (3*m) $ insert (4*m-1) s')

             where (m, s') = deleteFindMin s

-- Reinhard Zumkeller, Jun 01 2011

CROSSREFS

Cf. A191113, A191180, A191181.

Sequence in context: A060141 A107757 A191180 * A057261 A003597 A018705

Adjacent sequences:  A191125 A191126 A191127 * A191129 A191130 A191131

KEYWORD

nonn

AUTHOR

Clark Kimberling, May 27 2011

STATUS

approved

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Last modified August 8 13:52 EDT 2020. Contains 336298 sequences. (Running on oeis4.)