A147795 - OEIS

%I #8 Sep 08 2013 19:59:24

%S 0,0,1,1,2,2,3,3,6,6,7,7,8,8,9,9,12,12,13,13,14,14,15,15,18,18,19,19,

%T 20,20,21,21,28,28,29,29,30,30,31,31,34,34,35,35,36,36,37,37,40,40,41,

%U 41,42,42,43,43,46,46,47,47,48,48,49,49

%N If n=A000695(k_n)+2*A000695(l_n), then a(n) is the number of nonnegative integers m<n such that k_m differs from k_n and l_m differs from l_n.

%C Let us call integers m and n collinear one to another if either A059905(m)=A059905(n) or A059906(m)=A059906(n). Then a(n) is the number of noncollinear to n nonnegative integers not exceeding n.

%F Theorem: a(2n)=a(2n+1).

%Y Cf. A000695, A054238, A059905, A059906.

%K nonn

%O 0,5

%A _Vladimir Shevelev_, Nov 13 2008

%E More terms from _Philippe Deléham_, Oct 18 2011