

A049906


a(n) = a(1) + a(2) + ... + a(n1)  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.


3



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
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OFFSET

1,2


LINKS



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(n2, 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)).


KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



