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A049905
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a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 3, where m = 2^(p+1) + 2 - n and p is the unique number such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = 2.
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1
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1, 2, 2, 3, 7, 12, 25, 50, 101, 153, 331, 675, 1355, 2714, 5429, 10858, 21717, 32577, 70583, 143881, 289121, 578922, 1158188, 2316554, 4633160, 9266371, 18532767, 37065547, 74131099, 148262202, 296524405, 593048810, 1186097621
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OFFSET
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1,2
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LINKS
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MAPLE
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s := proc(n) option remember; `if`(n < 1, 0, a(n) + s(n - 1)) end proc:
a := proc(n) option remember;
`if`(n < 3, [1, 2][n], s(n - 1) - a(2^ceil(log[2](n - 1)) + 2 - n)):
end proc:
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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