A049912 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, a(2) = 2, and a(3) = 4.

1, 2, 4, 6, 9, 21, 39, 73, 116, 270, 537, 1069, 2108, 4139, 7857, 14143, 22537, 52930, 105857, 211709, 423388, 846699, 1692977, 3384383, 6763017, 13511354, 26939388, 53561245, 105852901, 206635762, 393095153, 707276793, 1127311334

Offset

1,2

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, 2, 4][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: A192079 A079143 A192316 * A268868 A271927 A227526

Adjacent sequences: A049909 A049910 A049911 * A049913 A049914 A049915

Keyword

nonn

Author

Clark Kimberling

Extensions

Name edited by Petros Hadjicostas, Nov 15 2019

Status

approved