A049896 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) = 4.

1, 1, 4, 5, 7, 17, 31, 59, 94, 218, 433, 863, 1702, 3341, 6343, 11417, 18193, 42728, 85453, 170903, 341782, 683501, 1366663, 2732057, 5459473, 10907096, 21746932, 43237535, 85450189, 166807568, 317327677, 570952097, 910026706

Offset

1,3

Links

Michael De Vlieger, Table of n, a(n) for n = 1..3327

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(log[2](n - 1)) + 2*n - 3))
     end proc:
seq(a(n), n = 1..40); # Petros Hadjicostas, Nov 15 2019

Mathematica

Nest[Append[#1, Total@ #1 - #1[[-2^Ceiling[#3] + 2 #2 - 3]] ] & @@ {#1, #2, Log2[#2 - 1]} & @@ {#, Length@ # + 1} &, {1, 1, 4}, 30] (* Michael De Vlieger, Nov 15 2019 *)

Crossrefs

Sequence in context: A107289 A056659 A292321 * A029520 A123368 A292164

Adjacent sequences: A049893 A049894 A049895 * A049897 A049898 A049899

Keyword

nonn

Author

Clark Kimberling

Extensions

Name edited by Petros Hadjicostas, Nov 15 2019

Status

approved