%I
%S 1,2,3,7,15,29,59,119,242,478,957,1915,3834,7676,15366,30762,61584,
%T 123050,246101,492203,984410,1968828,3937670,7875370,15750800,
%U 31501723,63003682,126007843,252016644,504035207,1008074256,2016156202
%N a(n) = a(1) + a(2) + ... + a(n1) + a(m) for n >= 4, where m = n  1  2^p and p is the unique integer such that 2^p < n  1 <= 2^(p+1), starting with a(1) = 1, a(2) = 2, and a(3) = 3.
%p s := proc(n) option remember; `if`(n < 1, 0, a(n) + s(n  1)); end proc;
%p a := proc(n) option remember; `if`(n < 4, [1, 2, 3][n], s(n  1) + a(2^ceil(log[2](n  1)  1) + n  1)); end proc;
%p seq(a(n), n = 1 .. 40); # _Petros Hadjicostas_, Apr 23 2020
%Y Cf. A049910 (similar with minus a(m)), A049911 (similar with minus a(2*m)), A049959 (similar with plus a(2*m)).
%K nonn
%O 1,2
%A _Clark Kimberling_
%E Name edited by _Petros Hadjicostas_, Apr 23 2020
