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 A191131 Increasing sequence generated by these rules:  a(1)=1, and if x is in a then 3x and 4x+3 are in a. 9
 1, 3, 7, 9, 15, 21, 27, 31, 39, 45, 63, 81, 87, 93, 111, 117, 127, 135, 159, 183, 189, 243, 255, 261, 279, 327, 333, 351, 375, 381, 405, 447, 471, 477, 511, 543, 549, 567, 639, 729, 735, 759, 765, 783, 837, 975, 981, 999, 1023, 1047, 1053, 1119, 1125, 1143, 1215, 1311, 1335, 1341, 1407, 1413, 1431, 1503, 1527, 1533, 1623 (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 = 3; f = 1; g = 9; a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]   (* A191131 *) b = a/3; c = (a - 3)/4; r = Range[1, 1500]; d = Intersection[b, r] (* A191186 *) e = Intersection[c, r] (* A191187 *) PROG (Haskell) import Data.Set (singleton, deleteFindMin, insert) a191131 n = a191131_list !! (n-1) a191131_list = f \$ singleton 1    where f s = m : (f \$ insert (3*m) \$ insert (4*m+3) s')              where (m, s') = deleteFindMin s -- Reinhard Zumkeller, Jun 01 2011 CROSSREFS Cf. A191113, A191186, A191187. Note that A191131, A261524, A261871, and A282572 are very similar and easily confused with each other. Sequence in context: A070993 A261524 A261871 * A282572 A299642 A128539 Adjacent sequences:  A191128 A191129 A191130 * A191132 A191133 A191134 KEYWORD nonn AUTHOR Clark Kimberling, May 27 2011 STATUS approved

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Last modified February 18 03:40 EST 2020. Contains 332006 sequences. (Running on oeis4.)