A050031 a(n) = a(n-1) + a(m) for n >= 4, where m = 2*n - 2 - 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.

1, 1, 2, 3, 6, 7, 10, 17, 34, 35, 38, 45, 62, 97, 142, 239, 478, 479, 482, 489, 506, 541, 586, 683, 922, 1401, 1890, 2431, 3114, 4515, 6946, 11461, 22922, 22923, 22926, 22933, 22950, 22985, 23030, 23127, 23366, 23845, 24334

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

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

Crossrefs

Cf. A050027, A050035, A050039, A050043, A050047, A050051, A050055, A050059, A050063, A050067, A050071 (similar, but with different initial conditions).

Programs

Mathematica

Fold[Append[#1, #1[[-1]] + #1[[#2]]] &, {1, 1, 2}, Flatten@Table[2 k, {n, 5}, {k, 2^n}]] (* Ivan Neretin, Sep 06 2015 *)

PARI

lista(nn) = {nn = max(nn, 3); my(va = vector(nn)); va[1] = 1; va[2] = 1; va[3] = 2; for(n=4, nn, va[n] = va[n-1] + va[2*(n - 1 - 2^logint(n-2, 2))]); va; } \\ Petros Hadjicostas, May 10 2020

Extensions

Name edited by Petros Hadjicostas, May 10 2020