

A049888


a(n) = a(1) + a(2) + ... + a(n1)  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, 3, 5, 11, 21, 39, 62, 144, 287, 571, 1126, 2211, 4197, 7555, 12039, 28274, 56547, 113091, 226166, 452291, 904357, 1807875, 3612679, 7217516, 14390524, 28611429, 56544667, 110381012, 209984179, 377814215, 602188918
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OFFSET

1,3


LINKS

Table of n, a(n) for n=1..33.


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: A155954 A337347 A087581 * A117221 A073879 A073880
Adjacent sequences: A049885 A049886 A049887 * A049889 A049890 A049891


KEYWORD

nonn


AUTHOR

Clark Kimberling


EXTENSIONS

Name edited by Petros Hadjicostas, Nov 15 2019


STATUS

approved



