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A075311 a(1) = 1; for n > 1, a(n) = smallest number m > a(n-1) such that number of 1's in binary expansion of m is not already in the sequence. 5
1, 3, 5, 6, 9, 10, 12, 15, 17, 18, 20, 23, 24, 27, 29, 30, 33, 34, 36, 39, 40, 43, 45, 46, 48, 51, 53, 54, 57, 58, 60, 65, 66, 68, 71, 72, 75, 77, 78, 80, 83, 85, 86, 89, 90, 92, 96, 99, 101, 102, 105, 106, 108, 113, 114, 116, 120, 127, 129, 130, 132, 135, 136, 139, 141 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

If A000120(k) is in sequence then k is not.

Differs from A001969: 63 is not included since it has 6 bits set.

LINKS

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

Phil Carmody, Re: New sieve and a challenge

Jon Perry, New sieve and a challenge

EXAMPLE

We start with a(1)=1. Then 2 is not included since it has one bit set and 1 is in sequence. Next, 3 is included since it has 2 one bits and 2 is not in sequence. And so on.

PROG

(PARI) v=vector(1000): v[1]=1: for(curr=2, 1000, e=A000120(curr): if(v[e], continue, v[curr]=1)): for(k=1, 1000, if(v[k], print1(k", ")))

(Haskell)

a075311 n = a075311_list !! (n-1)

a075311_list = 1 : f 2 [1] where

   f x ys = if a000120 x `elem` ys then f (x + 1) ys

                                   else x : f (x + 1) (x : ys)

-- Reinhard Zumkeller, Apr 22 2012

CROSSREFS

Cf. A075517.

Cf. A217122.

Sequence in context: A241571 A080307 A001969 * A032786 A080309 A018900

Adjacent sequences:  A075308 A075309 A075310 * A075312 A075313 A075314

KEYWORD

easy,nonn

AUTHOR

Phil Carmody, Oct 11 2002

EXTENSIONS

Edited by Ralf Stephan, Sep 14 2003

STATUS

approved

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Last modified December 19 21:57 EST 2014. Contains 252240 sequences.