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A190810 Increasing sequence generated by these rules:  a(1)=1, and if x is in a then 2x+1 and 3x-1 are in a. 4
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, 83, 86, 89, 92, 95, 101, 104, 119, 122, 127, 131, 137, 140, 143, 149, 167, 173, 176, 179, 185, 188, 191, 194, 203, 209, 212, 239, 245, 248, 255, 257, 263, 266, 275, 281 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A190803.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MATHEMATICA

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

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

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

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

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

PROG

(Haskell)

import Data.Set (singleton, deleteFindMin, insert)

a190810 n = a190810_list !! (n-1)

a190810_list = f $ singleton 1

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

             where (m, s') = deleteFindMin s

-- Reinhard Zumkeller, Jun 01 2011

(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

CROSSREFS

Cf. A190803, A190855, A190856.

Sequence in context: A174895 A186285 A190855 * A278591 A191121 A026401

Adjacent sequences:  A190807 A190808 A190809 * A190811 A190812 A190813

KEYWORD

nonn

AUTHOR

Clark Kimberling, May 20 2011

EXTENSIONS

a(55)=255 inserted by Reinhard Zumkeller, Jun 01 2011

STATUS

approved

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Last modified September 21 23:55 EDT 2019. Contains 327286 sequences. (Running on oeis4.)