cp's OEIS Frontend

A191125 Increasing sequence generated by these rules: a(1)=1, and if x is in a then 3x-1 and 4x+3 are in a.

%I A191125 #10 Jul 13 2013 12:04:10
%S A191125 1,2,5,7,11,14,20,23,31,32,41,47,59,68,83,92,95,122,127,131,140,167,
%T A191125 176,191,203,239,248,275,284,335,365,371,380,383,392,419,491,500,511,
%U A191125 527,563,572,608,671,707,716,743,767,815,824,851,959,995,1004,1094,1103,1112,1139,1148,1175,1256,1343,1463,1472,1487,1499,1523
%N A191125 Increasing sequence generated by these rules:  a(1)=1, and if x is in a then 3x-1 and 4x+3 are in a.
%C A191125 See A191113.
%H A191125 Reinhard Zumkeller, <a href="/A191125/b191125.txt">Table of n, a(n) for n = 1..10000</a>
%t A191125 h = 3; i = -1; j = 4; k = 3; f = 1; g = 9;
%t A191125 a = Union[
%t A191125   Flatten[NestList[{h # + i, j # + k} &, f, g]]]  (* A191125 *)
%t A191125 b = (a + 1)/3; c = (a - 3)/4; r = Range[1, 1500];
%t A191125 d = Intersection[b, r] (* A191174 *)
%t A191125 e = Intersection[c, r] (* A191175 *)
%o A191125 (Haskell)
%o A191125 import Data.Set (singleton, deleteFindMin, insert)
%o A191125 a191125 n = a191125_list !! (n-1)
%o A191125 a191125_list = f $ singleton 1
%o A191125    where f s = m : (f $ insert (3*m-1) $ insert (4*m+3) s')
%o A191125              where (m, s') = deleteFindMin s
%o A191125 -- _Reinhard Zumkeller_, Jun 01 2011
%Y A191125 Cf. A191113.
%K A191125 nonn
%O A191125 1,2
%A A191125 _Clark Kimberling_, May 27 2011