A049892 - OEIS

%I #10 Nov 16 2019 03:29:09

%S 1,1,3,4,6,14,26,49,78,181,360,717,1414,2776,5270,9486,15116,35501,

%T 71000,141997,283974,567896,1135510,2269966,4536076,9062306,18068728,

%U 35924482,70997428,138594290,263655928,474383156,756107812

%N a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2*n - 3 - 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) = 3.

%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, 3][n], s(n - 1) - a(-2^ceil(log[2](n - 1)) + 2*n - 3)):

%p end proc:

%p seq(a(n), n = 1..40); # _Petros Hadjicostas_, Nov 15 2019

%K nonn

%O 1,3

%A _Clark Kimberling_

%E Name edited by _Petros Hadjicostas_, Nov 15 2019