A190810 - OEIS

%I #12 Jul 14 2016 16:05:30

%S 1,2,3,5,7,8,11,14,15,17,20,23,29,31,32,35,41,44,47,50,59,63,65,68,71,

%T 83,86,89,92,95,101,104,119,122,127,131,137,140,143,149,167,173,176,

%U 179,185,188,191,194,203,209,212,239,245,248,255,257,263,266,275,281

%N Increasing sequence generated by these rules:  a(1)=1, and if x is in a then 2x+1 and 3x-1 are in a.

%C See A190803.

%H Reinhard Zumkeller, <a href="/A190810/b190810.txt">Table of n, a(n) for n = 1..10000</a>

%t h = 2; i = 1; j = 3; k = -1; f = 1; g = 9 ;

%t a = Union[Flatten[NestList[{h # + i, j # + k} &, f, g]]]  (* A190810 *)

%t b = (a - 1)/2; c = (a + 1)/3; r = Range[1, 900];

%t d = Intersection[b, r] (* A190855 *)

%t e = Intersection[c, r] (* A190856 *)

%o (Haskell)

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

%o a190810 n = a190810_list !! (n-1)

%o a190810_list = f $ singleton 1

%o    where f s = m : (f $ insert (2*m+1) $ insert (3*m-1) s')

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

%o -- _Reinhard Zumkeller_, Jun 01 2011

%o (PARI) is(n)=if(n<7, n!=4, (n%3==1 && is(n\3)) || (n%2 && is(n\2))) \\ _Charles R Greathouse IV_, Jul 14 2016

%Y Cf. A190803, A190855, A190856.

%K nonn

%O 1,2

%A _Clark Kimberling_, May 20 2011

%E a(55)=255 inserted by _Reinhard Zumkeller_, Jun 01 2011