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 A006581 a(n) = Sum_{k=1..n-1} (k AND n-k). (Formerly M3225) 6
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,3 REFERENCES Marc LeBrun, personal communication. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Alois P. Heinz, Table of n, a(n) for n = 2..8191 M. Le Brun, Email to N. J. A. Sloane, Jul 1991 FORMULA 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). CROSSREFS 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 KEYWORD nonn AUTHOR STATUS approved

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Last modified April 19 03:45 EDT 2021. Contains 343105 sequences. (Running on oeis4.)