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A049936
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) = 2.
0
1, 1, 2, 5, 11, 21, 43, 95, 222, 402, 805, 1619, 3270, 6719, 14021, 30507, 71765, 129510, 259021, 518051, 1036134, 2072447, 4145477, 8293419, 16597589, 33252922, 66693100, 134163313, 271435969, 555324050, 1160743611, 2526230091
OFFSET
1,3
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, 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
Sequence in context: A364552 A369525 A364591 * A058358 A292528 A135119
KEYWORD
nonn
EXTENSIONS
Name edited by Petros Hadjicostas, Nov 15 2019
STATUS
approved