A049915 - OEIS

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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.

1, 2, 4, 5, 7, 17, 31, 50, 67, 182, 361, 710, 1387, 2642, 4756, 7580, 10222, 28022, 56041, 112070, 224107, 448082, 895636, 1789340, 3573742, 7127042, 14170036, 28004060, 54666862, 103996022, 187115026, 298238090, 402234112

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

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

PROG

(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)

CROSSREFS

Cf. A049914 (similar, but with minus a(m/2)), A049962 (similar, but with plus a(m/2)), A049963 (similar, but with plus a(m)).

Sequence in context: A290431 A220701 A005620 * A244332 A119909 A301521

Adjacent sequences: A049912 A049913 A049914 * A049916 A049917 A049918

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Name edited by Petros Hadjicostas, Apr 26 2020

STATUS

approved