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URL: https://oeis.org/A049927

⇱ A049927 - OEIS


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A049927
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.
0
1, 3, 3, 4, 7, 15, 29, 47, 62, 168, 335, 659, 1286, 2451, 4411, 7030, 9481, 25989, 51977, 103943, 207854, 415587, 830683, 1659574, 3314569, 6610179, 13142404, 25973164, 50702341, 96454077, 173545169, 276609425, 373063502, 1022736426
OFFSET
1,2
PROG
(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
CROSSREFS
Sequence in context: A373457 A011959 A246023 * A329216 A266616 A360846
KEYWORD
nonn
STATUS
approved