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A049921 a(n) = a(1) + a(2) + ... + 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.

%I A049921 #11 Nov 14 2019 15:46:05
%S A049921 1,3,2,3,8,14,29,57,116,176,380,775,1556,3117,6235,12469,24940,37412,
%T A049921 81058,165234,332029,664839,1330073,2660350,5320760,10641579,21283186,
%U A049921 42566387,85132780,170265565,340531131,681062261,1362124524
%N A049921 a(n) = a(1) + a(2) + ... + 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.
%p A049921 s := proc(n) option remember; `if`(n < 1, 0, a(n) + s(n - 1)) end proc:
%p A049921 a := proc(n) option remember;
%p A049921 `if`(n < 4, [1, 3, 2][n], s(n - 1) - a(2^ceil(log[2](n - 1)) + 2 - n)):
%p A049921 end proc:
%p A049921 seq(a(n), n = 1..34); # _Petros Hadjicostas_, Nov 14 2019
%K A049921 nonn
%O A049921 1,2
%A A049921 _Clark Kimberling_
%E A049921 Name edited by _Petros Hadjicostas_, Nov 14 2019