A191132 - OEIS

%I #8 Jul 13 2013 12:04:10

%S 1,4,13,40,49,121,148,157,193,364,445,472,481,580,589,625,769,1093,

%T 1336,1417,1444,1453,1741,1768,1777,1876,1885,1921,2308,2317,2353,

%U 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 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 See A191113.

%H Reinhard Zumkeller, <a href="/A191132/b191132.txt">Table of n, a(n) for n = 1..10000</a>

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

%t a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]   (* A191132 *)

%t b = (a - 1)/3; c = (a + 3)/4; r = Range[1, 2500];

%t d = Intersection[b, r] (* A191188 *)

%t e = Intersection[c, r] (* A191189 *)

%o (Haskell)

%o import Data.Set (singleton, deleteFindMin, insert)

%o a191132 n = a191132_list !! (n-1)

%o a191132_list = 1 : f (singleton 4)

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

%o              where (m, s') = deleteFindMin s

%o -- _Reinhard Zumkeller_, Jun 01 2011

%Y Cf. A191113.

%K nonn

%O 1,2

%A _Clark Kimberling_, May 27 2011