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A051145 a(0)=0, a(1)=1, a(n) = smallest number such that sequence b(n) = a(n) OR a(n+1) is strictly monotonically increasing. 7
0, 1, 2, 4, 3, 8, 4, 9, 6, 16, 7, 24, 32, 25, 34, 28, 35, 64, 36, 65, 38, 72, 39, 80, 40, 81, 42, 84, 43, 128, 44, 129, 46, 144, 47, 192, 48, 193, 50, 196, 51, 200, 52, 201, 54, 256, 55, 264, 64, 265, 66, 268, 67, 272, 68, 273, 70, 280, 71, 288, 72, 289, 74, 292, 75, 304 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(A051147(n))) = 2^n; A209229(a(A244747(n))) = 1. - Reinhard Zumkeller, Jul 06 2014

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

FORMULA

a(n) = ((a(n-1) OR a(n-2)) + 1) AND NOT a(n-1). - Charlie Neder, Oct 12 2018

EXAMPLE

To find a(6): we have a(4)=3=11, a(5)=8=1000, 3 OR 8 = 1011 = 11, smallest number which when OR-ed with 8 gives a number bigger than 11 is 4, since then 4=100 OR 8=1000 = 1100=12; so a(6)=4, b(6)=12 (cf. A051146).

MATHEMATICA

a[0] = 0; a[1] = 1; a[n_] := a[n] = (b = 0; While[b++; BitOr[b, a[n-1]] <= BitOr[a[n-2], a[n-1]]]; b); Table[a[n], {n, 0, 65}] (* Jean-Fran├žois Alcover, Oct 07 2011 *)

PROG

(Haskell)

import Data.Bits ((.|.))

a051145 n = a051145_list !! n

a051145_list = 0 : 1 : f 1 1 where

   f x b = y : f y z where

     (y, z) = head [(y, z) | y <- [1..],

                             let z = x .|. y :: Integer, z > b]

-- Reinhard Zumkeller, Oct 25 2012

CROSSREFS

Cf. A051146, A051147, A057923-A057931, A209229, A244747.

Sequence in context: A124256 A108503 A052131 * A288966 A057495 A180246

Adjacent sequences:  A051142 A051143 A051144 * A051146 A051147 A051148

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane, E. M. Rains

EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), Oct 03 2000

STATUS

approved

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Last modified May 26 04:46 EDT 2019. Contains 323579 sequences. (Running on oeis4.)