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A006581
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a(n) = Sum_{k=1..n-1} (k AND n-k).
(Formerly M3225)
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4
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1, 0, 4, 4, 5, 0, 12, 16, 21, 16, 24, 20, 17, 0, 32, 48, 65, 64, 84, 84, 85, 64, 92, 96, 101, 80, 88, 68, 49, 0, 80, 128, 177, 192, 244, 260, 277, 256, 316, 336, 357, 336, 360, 340, 321, 256, 336, 368, 401, 384, 420, 404, 389, 320, 364, 352, 341, 272, 264, 196
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OFFSET
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2,3
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REFERENCES
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Marc LeBrun, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 2..8191
M. Le Brun, Email to N. J. A. Sloane, Jul 1991
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FORMULA
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G.f.: 1/(1-x)^2 * Sum_{k>=0} 2^k*t^2/(1+t)^2, t = x^2^k. - Ralf Stephan, Feb 12 2003
a(0) = a(1) = 0, a(2n) = 2a(n-1) + 2a(n) + n, a(2n+1) = 4a(n).
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CROSSREFS
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Cf. A090889(n) - A000292(n-2).
Antidiagonal sums of array A003985.
Sequence in context: A255241 A200694 A021696 * A255902 A019922 A092171
Adjacent sequences: A006578 A006579 A006580 * A006582 A006583 A006584
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane
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STATUS
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approved
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