%I #10 Nov 20 2019 01:41:32
%S 1,1,4,5,6,16,28,45,61,166,328,645,1261,2401,4323,6890,9291,25471,
%T 50938,101865,203701,407281,814083,1626410,3248331,6478081,12879768,
%U 25454120,49689111,94526551,170077063,271081695,365608246,1002298186
%N a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2*n - 2 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = 1 and a(3) = 4.
%p s := proc(n) option remember; `if`(n < 1, 0, a(n) + s(n - 1)) end proc:
%p a := proc(n) option remember;
%p `if`(n < 4, [1, 1, 4][n], s(n - 1) - a(-2^ceil(log[2](n - 1)) + 2*n - 2)):
%p end proc:
%p seq(a(n), n = 1..40); # _Petros Hadjicostas_, Nov 19 2019
%K nonn
%O 1,3
%A _Clark Kimberling_
%E Name edited by _Petros Hadjicostas_, Nov 19 2019