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A006581 a(n) = Sum_{k=1..n-1} (k AND n-k).
(Formerly M3225)
4
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

N. J. A. Sloane

STATUS

approved

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Last modified February 18 13:07 EST 2018. Contains 299322 sequences. (Running on oeis4.)