A049906 a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = n - 1 - 2^p 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) = 2.

1, 2, 2, 4, 7, 15, 29, 58, 114, 231, 461, 922, 1842, 3681, 7354, 14694, 29359, 58775, 117549, 235098, 470194, 940385, 1880762, 3761510, 7522991, 15045926, 30091735, 60183240, 120366019, 240731118, 481460397, 962917121, 1925826902

Offset

1,2

Links

Table of n, a(n) for n=1..33.

Prog

(PARI) lista(nn) = { nn = max(nn, 3); my(va = vector(nn)); va[1] = 1; va[2] = 2; va[3] = 2; my(sa = vecsum(va)); for (n=4, nn, va[n] = sa - va[n - 1 - 2^logint(n-2, 2)]; sa += va[n]; ); va; } \\ Petros Hadjicostas, May 03 2020

Crossrefs

Cf. A049907 (similar, but with minus a(2*m)), A049954 (similar, but with plus a(m)), A049955 (similar, but with plus a(2*m)).

Sequence in context: A120363 A118988 A049904 * A014265 A153967 A052949

Adjacent sequences: A049903 A049904 A049905 * A049907 A049908 A049909

Keyword

nonn

Author

Clark Kimberling

Extensions

Name edited by Petros Hadjicostas, May 03 2020

Status

approved