cp's OEIS Frontend

A049915 a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2*n - 2 - 2^(p+1) 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) = 4.

%I A049915 #24 May 06 2022 13:12:15
%S A049915 1,2,4,5,7,17,31,50,67,182,361,710,1387,2642,4756,7580,10222,28022,
%T A049915 56041,112070,224107,448082,895636,1789340,3573742,7127042,14170036,
%U A049915 28004060,54666862,103996022,187115026,298238090,402234112
%N A049915 a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2*n - 2 - 2^(p+1) 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) = 4.
%o A049915 (PARI) lista(nn) = { my(va = vector(nn)); va[1] = 1; va[2] = 2; va[3] = 4; my(sa = vecsum(va)); for (n=4, nn, va[n] = sa - va[2*n - 2 - 2^ceil(log(n-1)/log(2))]; sa += va[n]; ); va; } \\ _Petros Hadjicostas_, Apr 26 2020 (with nn > 2)
%Y A049915 Cf. A049914 (similar, but with minus a(m/2)), A049962 (similar, but with plus a(m/2)), A049963 (similar, but with plus a(m)).
%K A049915 nonn
%O A049915 1,2
%A A049915 _Clark Kimberling_
%E A049915 Name edited by _Petros Hadjicostas_, Apr 26 2020