A049960 a(n) = a(1) + a(2) + ... + a(n-1) + a(m) for n >= 3, where m = 2*n - 3 - 2^(p+1) and p is the unique integer such that 2^p < n-1 <= 2^(p+1), with a(1) = 1 and a(2) = 2.

1, 2, 4, 8, 19, 35, 73, 161, 376, 680, 1363, 2741, 5536, 11375, 23737, 51647, 121495, 219254, 438511, 877037, 1754128, 3508559, 7018105, 14040383, 28098967, 56295692, 112908400, 227132417, 459528811, 940138484, 1965086401, 4276793213, 10059144016, 18153201632, 36306403267

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

Cf. A006257, A049939, A049940, A049964.

Programs

Maple

a := proc(n) option remember; if n<3 then return [1,2][n] fi; add(a(i), i=1..n-1) + a(2*(n-2) - Bits:-Iff(n-2, n-2)) end: seq(a(n), n=1..37); # Petros Hadjicostas, Sep 24 2019 by modifying a program by Peter Luschny

Formula

a(n) = a(A006257(n-2)) + Sum_{i = 1..n-1} a(i) for n >= 3 with a(1) = 1 and a(2) = 2. - Petros Hadjicostas, Sep 24 2019

Extensions

Name edited and more terms from Petros Hadjicostas, Sep 24 2019