A175343 a(1)=1. a(n) = the smallest positive integer not yet occurring in the sequence such that (binary a(n)) OR (binary a(n-1)) is 2^k -1 for some k >=1.

1, 2, 3, 4, 7, 5, 6, 9, 14, 11, 12, 15, 8, 23, 10, 13, 18, 29, 19, 28, 27, 20, 31, 16, 47, 17, 30, 21, 26, 37, 58, 39, 24, 55, 25, 22, 41, 54, 43, 52, 59, 36, 63, 32, 95, 33, 62, 35, 60, 51, 44, 83, 45, 50, 61, 34, 93, 38, 57, 46, 49, 78, 53, 42, 85, 106, 87, 40, 119, 56, 71

Offset

1,2

Comments

By "(binary a(n)) OR (binary a(n-1))", it is meant: Write a(n) and a(n-1) in binary (with the smallest, and only the smallest, of the two padded with the appropriate number of leading 0's so that both representations are the same number of binary digits long). OR respective binary digits. Here, each pair of respective digits OR'ed should be 1.

Links

Ivan Neretin, Table of n, a(n) for n = 1..10000

Maple

Contribution from R. J. Mathar, Oct 09 2010: (Start)
isA000079 := proc(n) if type(n, 'even') then nops(numtheory[factorset](n)) = 1 ; else false ; fi ; end proc: read("transforms") ;
A175343 := proc(n) option remember; if n = 1 then 1; else for a from 1 do earl := false; for j from 1 to n-1 do if procname(j) = a then earl := true; break; end if; od ; if not earl then if isA000079(ORnos(a, procname(n-1))+1 ) then return a; end if; end if; end do: end if; end proc:
seq(A175343(n), n=1..80) ; (End)

Crossrefs

A109812

Sequence in context: A361646 A359051 A014321 * A239965 A072767 A071651

Adjacent sequences: A175340 A175341 A175342 * A175344 A175345 A175346

Keyword

base,nonn

Author

Leroy Quet, Apr 17 2010

Extensions

More terms from R. J. Mathar, Oct 09 2010

Status

approved