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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.

%I A050043 #15 May 15 2020 10:25:11
%S A050043 1,2,1,3,6,8,11,19,38,40,43,51,70,110,161,271,542,544,547,555,574,614,
%T A050043 665,775,1046,1590,2145,2759,3534,5124,7883,13007,26014,26016,26019,
%U A050043 26027,26046,26086,26137,26247,26518,27062,27617
%N 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.
%H A050043 Ivan Neretin, <a href="/A050043/b050043.txt">Table of n, a(n) for n = 1..8193</a>
%t A050043 Fold[Append[#1, #1[[-1]] + #1[[#2]]] &, {1, 2, 1}, Flatten@Table[2 k, {n, 5}, {k, 2^n}]] (* _Ivan Neretin_, Sep 06 2015 *)
%o A050043 (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
%Y A050043 Cf. A050027, A050031, A050035, A050039, A050047, A050051, A050055, A050059, A050063, A050067, A050071 (similar, but with different initial conditions).
%K A050043 nonn
%O A050043 1,2
%A A050043 _Clark Kimberling_
%E A050043 Name edited by _Petros Hadjicostas_, May 15 2020