cp's OEIS Frontend

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.

%I A191132 #8 Jul 13 2013 12:04:10
%S A191132 1,4,13,40,49,121,148,157,193,364,445,472,481,580,589,625,769,1093,
%T A191132 1336,1417,1444,1453,1741,1768,1777,1876,1885,1921,2308,2317,2353,
%U A191132 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
%N 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.
%C A191132 See A191113.
%H A191132 Reinhard Zumkeller, <a href="/A191132/b191132.txt">Table of n, a(n) for n = 1..10000</a>
%t A191132 h = 3; i = 1; j = 4; k = -3; f = 1; g = 9;
%t A191132 a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]   (* A191132 *)
%t A191132 b = (a - 1)/3; c = (a + 3)/4; r = Range[1, 2500];
%t A191132 d = Intersection[b, r] (* A191188 *)
%t A191132 e = Intersection[c, r] (* A191189 *)
%o A191132 (Haskell)
%o A191132 import Data.Set (singleton, deleteFindMin, insert)
%o A191132 a191132 n = a191132_list !! (n-1)
%o A191132 a191132_list = 1 : f (singleton 4)
%o A191132    where f s = m : (f $ insert (3*m+1) $ insert (4*m-3) s')
%o A191132              where (m, s') = deleteFindMin s
%o A191132 -- _Reinhard Zumkeller_, Jun 01 2011
%Y A191132 Cf. A191113.
%K A191132 nonn
%O A191132 1,2
%A A191132 _Clark Kimberling_, May 27 2011