cp's OEIS Frontend

A049957 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) = 2, and a(3) = 3.

%I A049957 #15 Nov 12 2019 11:14:44
%S A049957 1,2,3,8,15,37,69,137,273,682,1296,2560,5098,10189,20373,40745,81489,
%T A049957 203722,387072,763960,1522829,3043120,6084976,12169338,24338267,
%U A049957 48676398,97352728,194705424,389410826,778821645,1557643285,3115286569,6230573137,15576432842,29595222400
%N A049957 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) = 2, and a(3) = 3.
%p A049957 s := proc(n) option remember; `if`(n < 1, 0, a(n) + s(n - 1)) end proc:
%p A049957 a := proc(n) option remember;
%p A049957 `if`(n < 4, [1, 2, 3][n], s(n - 1) + a(2^ceil(log[2](n - 1)) + 2 - n)):
%p A049957 end proc:
%p A049957 seq(a(n), n = 1..34); # _Petros Hadjicostas_, Nov 11 2019
%Y A049957 Cf. A006257, A049933, A049937, A049945.
%K A049957 nonn
%O A049957 1,2
%A A049957 _Clark Kimberling_
%E A049957 Name edited by and more terms from _Petros Hadjicostas_, Nov 11 2019