A050054 a(n) = a(n-1) + a(m) for n >= 4, where m = n - 1 - 2^p 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, 5, 7, 8, 10, 14, 19, 20, 22, 26, 31, 38, 46, 56, 70, 71, 73, 77, 82, 89, 97, 107, 121, 140, 160, 182, 208, 239, 277, 323, 379, 380, 382, 386, 391, 398, 406, 416, 430, 449, 469, 491, 517, 548, 586, 632

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..8193

Maple

a := proc(n) option remember;
     `if`(n < 4, [1, 2, 4][n], a(n - 1) + a(-2^ceil(-1+log[2](n - 1)) + n - 1)):
     end proc:
seq(a(n), n = 1..40); # Petros Hadjicostas, Nov 18 2019

Mathematica

Fold[Append[#1, #1[[-1]] + #1[[#2]]] &, {1, 2, 4}, Flatten@Table[k, {n, 5}, {k, 2^n}]] (* Ivan Neretin, Sep 08 2015 *)

Crossrefs

Cf. similar sequences with different initial conditions listed in A050034.

Sequence in context: A108513 A029749 A018519 * A018371 A127964 A269929

Adjacent sequences: A050051 A050052 A050053 * A050055 A050056 A050057

Keyword

nonn

Author

Clark Kimberling

Extensions

Name edited by Petros Hadjicostas, Nov 18 2019

Status

approved