A049927 - OEIS

%I #9 Apr 26 2020 13:55:03

%S 1,3,3,4,7,15,29,47,62,168,335,659,1286,2451,4411,7030,9481,25989,

%T 51977,103943,207854,415587,830683,1659574,3314569,6610179,13142404,

%U 25973164,50702341,96454077,173545169,276609425,373063502,1022736426

%N 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 and a(2) = a(3) = 3.

%o (PARI) lista(nn) = { my(va = vector(nn)); va[1] = 1; va[2] = 3; va[3] = 3; 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

%K nonn

%O 1,2

%A _Clark Kimberling_