A050043 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) = 1, a(2) = 2, and a(3) = 1.

1, 2, 1, 3, 6, 8, 11, 19, 38, 40, 43, 51, 70, 110, 161, 271, 542, 544, 547, 555, 574, 614, 665, 775, 1046, 1590, 2145, 2759, 3534, 5124, 7883, 13007, 26014, 26016, 26019, 26027, 26046, 26086, 26137, 26247, 26518, 27062, 27617

Offset

1,2

Links

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

Mathematica

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

Prog

(PARI) lista(nn) = {nn = max(nn, 3); my(va = vector(nn)); va[1] = 1; va[2] = 2; va[3] = 1; for(n=4, nn, va[n] = va[n-1] + va[2*(n - 1 - 2^logint(n-2, 2))]); va; } \\ Petros Hadjicostas, May 15 2020

Crossrefs

Cf. A050027, A050031, A050035, A050039, A050047, A050051, A050055, A050059, A050063, A050067, A050071 (similar, but with different initial conditions).

Sequence in context: A021472 A258047 A053225 * A113396 A294284 A295678

Adjacent sequences: A050040 A050041 A050042 * A050044 A050045 A050046

Keyword

nonn

Author

Clark Kimberling

Extensions

Name edited by Petros Hadjicostas, May 15 2020

Status

approved