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

Author

Leroy Quet, Apr 17 2010

Keywords

• base
• nonn

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

Crossrefs

A109812

Programs

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)

Extensions

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