A050026 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) = a(2) = a(3) = 1.

1, 1, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 13, 16, 20, 25, 31, 32, 33, 34, 36, 39, 43, 48, 54, 62, 71, 81, 92, 105, 121, 141, 166, 167, 168, 169, 171, 174, 178, 183, 189, 197, 206, 216, 227, 240, 256, 276, 301

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

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

Programs

Mathematica

Fold[Append[#1, #1[[-1]] + #1[[#2]]] &, {1, 1, 1}, Flatten@Table[k, {n, 5}, {k, 2^n}]] (* Ivan Neretin, Aug 30 2015 *)

PARI

lista(nn) = {nn = max(nn,3); my(va = vector(nn)); va[1] = 1; va[2] = 1; va[3] = 1; for(n=4, nn, va[n] = va[n-1] + va[n - 1 - 2^logint(n-2, 2)]); va;} \\ Petros Hadjicostas, May 03 2020

Extensions

Name edited by Petros Hadjicostas, Apr 25 2020