A049952 - OEIS

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A049952

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) = 1 and a(2) = a(3) = 2.

1, 2, 2, 6, 13, 25, 51, 113, 264, 478, 957, 1925, 3888, 7989, 16671, 36273, 85329, 153988, 307977, 615965, 1231968, 2464149, 4928991, 9860913, 19734609, 39537876, 79298400, 159520791, 322738605, 660282828, 1380129447, 3003699099

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

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

end proc:

seq(a(n), n = 1..40); # Petros Hadjicostas, Nov 15 2019

CROSSREFS