Voozh

A049946

a(n) = a(1) + a(2) + ... + a(n-1) + 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) = a(2) = 1 and a(3) = 4.

1, 1, 4, 7, 14, 28, 56, 115, 233, 460, 920, 1843, 3689, 7385, 14784, 29596, 59251, 118388, 236776, 473555, 947113, 1894233, 3788480, 7576988, 15154035, 30308188, 60616603, 121233666, 242468255, 484938356, 969880408, 1939768215

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..32.

MAPLE

s := proc(n) option remember; `if`(n < 1, 0, a(n) + s(n - 1)) end proc:

a := proc(n) option remember;

`if`(n < 4, [1, 1, 4][n], s(n - 1) + a(-2^ceil(-1 + log[2](n - 1)) + n - 1)):

end proc:

seq(a(n), n = 1..40); # Petros Hadjicostas, Apr 25 2020

CROSSREFS