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a(n) = a(n-1) + a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 3, and a(3) = 2.
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%I #17 Nov 11 2019 01:44:05

%S 1,3,2,5,6,11,13,16,17,33,46,57,63,68,70,73,74,147,217,285,348,405,

%T 451,484,501,517,530,541,547,552,554,557,558,1115,1669,2221,2768,3309,

%U 3839,4356,4857,5341,5792,6197,6545,6830,7047,7194

%N a(n) = a(n-1) + a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 3, and a(3) = 2.

%H Ivan Neretin, <a href="/A050061/b050061.txt">Table of n, a(n) for n = 1..8193</a>

%p a := proc(n) option remember;

%p `if`(n < 4, [1, 3, 2][n], a(n - 1) + a(2^ceil(log[2](n - 1)) + 2 - n)); end proc;

%p seq(a(n), n = 1..50); # _Petros Hadjicostas_, Nov 11 2019

%t Fold[Append[#1, #1[[-1]] + #1[[#2]]] &, {1, 3, 2}, Flatten@Table[k, {n, 5}, {k, 2^n, 1, -1}]] (* _Ivan Neretin_, Sep 08 2015 *)

%Y Cf. similar sequences with different initial conditions: A050025 (1,1,1), A050029 (1,1,2), A050033 (1,1,3), A050037 (1,1,4), A050041 (1,2,1), A050045 (1,2,2), A050049 (1,2,3), A050053 (1,2,4), A050057 (1,3,1), A050065 (1,3,3), A050069 (1,3,4).

%K nonn

%O 1,2

%A _Clark Kimberling_

%E Name edited by _Petros Hadjicostas_, Nov 11 2019