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a(n) = log_2(A110428(n)). Also, a(n) = a(n-1) + a(m) for n >= 3, 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) = 0 and a(2) = 1.
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%I #16 Nov 14 2019 10:42:55

%S 0,1,1,2,2,4,5,6,6,12,17,21,23,25,26,27,27,54,80,105,128,149,166,178,

%T 184,190,195,199,201,203,204,205,205,410,614,817,1018,1217,1412,1602,

%U 1786,1964,2130,2279,2407,2512,2592,2646,2673,2700,2726,2751,2774,2795,2812,2824,2830

%N a(n) = log_2(A110428(n)). Also, a(n) = a(n-1) + a(m) for n >= 3, 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) = 0 and a(2) = 1.

%F 2^a(n) = A110428(n).

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

%p `if`(n < 3, [0, 1][n], a(n - 1) + a(2^ceil(log[2](n - 1)) + 2 - n)); end proc;

%p seq(a(n), n = 1..50); #

%Y Cf. A050049, A050069, A110428.

%K nonn

%O 1,4

%A _Petros Hadjicostas_, Nov 13 2019