cp's OEIS Frontend

A049905 a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 3, where m = 2^(p+1) + 2 - n and p is the unique number such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = 2.

%I A049905 #12 Nov 12 2019 11:16:58
%S A049905 1,2,2,3,7,12,25,50,101,153,331,675,1355,2714,5429,10858,21717,32577,
%T A049905 70583,143881,289121,578922,1158188,2316554,4633160,9266371,18532767,
%U A049905 37065547,74131099,148262202,296524405,593048810,1186097621
%N A049905 a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 3, where m = 2^(p+1) + 2 - n and p is the unique number such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = 2.
%p A049905 s := proc(n) option remember; `if`(n < 1, 0, a(n) + s(n - 1)) end proc:
%p A049905 a := proc(n) option remember;
%p A049905 `if`(n < 3, [1, 2][n], s(n - 1) - a(2^ceil(log[2](n - 1)) + 2 - n)):
%p A049905 end proc:
%p A049905 seq(a(n), n = 1..34); # _Petros Hadjicostas_, Nov 11 2019
%K A049905 nonn
%O A049905 1,2
%A A049905 _Clark Kimberling_
%E A049905 Name edited by _Petros Hadjicostas_, Nov 11 2019