A049911 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) = 3.

1, 2, 3, 4, 6, 14, 26, 42, 56, 152, 302, 594, 1160, 2210, 3978, 6340, 8550, 23438, 46874, 93738, 187448, 374786, 749130, 1496644, 2989158, 5961218, 11852136, 23423224, 45724590, 86984606, 156507206, 249453030, 336437636, 922328300

Offset

1,2

Links

Table of n, a(n) for n=1..34.

Formula

a(n) = 2*A049887(n) for n > 3.

Prog

(PARI) lista(nn) = { my(va = vector(nn)); va[1] = 1; va[2] = 2; 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 (with nn > 2)

Crossrefs

Cf. A049887, A049910 (similar, but with minus a(m/2)), A049958 (similar, but with plus a(m/2)), A049959 (similar, but with plus a(m)).

Sequence in context: A174046 A095991 A293714 * A056712 A204540 A280592

Adjacent sequences: A049908 A049909 A049910 * A049912 A049913 A049914

Keyword

nonn

Author

Clark Kimberling

Extensions

Name edited by Petros Hadjicostas, Apr 26 2020

Status

approved