|
%I #11 Dec 15 2016 10:42:38
%S 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,
%T 30,21,26,37,58,39,24,55,25,22,41,54,43,52,59,36,63,32,95,33,62,35,60,
%U 51,44,83,45,50,61,34,93,38,57,46,49,78,53,42,85,106,87,40,119,56,71
%N 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.
%C 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.
%H Ivan Neretin, <a href="/A175343/b175343.txt">Table of n, a(n) for n = 1..10000</a>
%p Contribution from _R. J. Mathar_, Oct 09 2010: (Start)
%p isA000079 := proc(n) if type(n,'even') then nops(numtheory[factorset](n)) = 1 ; else false ; fi ; end proc: read("transforms") ;
%p 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:
%p seq(A175343(n),n=1..80) ; (End)
%Y A109812
%K base,nonn
%O 1,2
%A _Leroy Quet_, Apr 17 2010
%E More terms from _R. J. Mathar_, Oct 09 2010
|
