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A063695 Remove even-positioned bits from the binary expansion of n. 4
0, 0, 2, 2, 0, 0, 2, 2, 8, 8, 10, 10, 8, 8, 10, 10, 0, 0, 2, 2, 0, 0, 2, 2, 8, 8, 10, 10, 8, 8, 10, 10, 32, 32, 34, 34, 32, 32, 34, 34, 40, 40, 42, 42, 40, 40, 42, 42, 32, 32, 34, 34, 32, 32, 34, 34, 40, 40, 42, 42, 40, 40, 42, 42, 0, 0, 2, 2, 0, 0, 2, 2, 8, 8, 10, 10, 8, 8, 10, 10, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

R. Stephan, Some divide-and-conquer sequences ...

R. Stephan, Table of generating functions

FORMULA

a(n) = 2*(floor(n/2)-a(floor(n/2))). - Vladeta Jovovic, Feb 23 2003

G.f. 1/(1-x) * sum(k>=0, (-2)^k*2t^2/(1-t^2), t=x^2^k). Members of A004514 written twice. - Ralf Stephan, Oct 06 2003

a(n) = 4 * a(floor(n / 4)) + 2 * floor(n mod 4 / 2). - Reinhard Zumkeller, Sep 26 2015

EXAMPLE

E.g. a(25) = 8 because 25 = 11001 in binary and when we AND this with 1010 we are left with 1000 = 8.

MAPLE

[seq(every_other_pos(j, 2, 1), j=0..120)]; Function every_other_pos given at A063694.

PROG

(Haskell)

a063695 0 = 0

a063695 n = 4 * a063695 n' + 2 * div q 2

            where (n', q) = divMod n 4

-- Reinhard Zumkeller, Sep 26 2015

CROSSREFS

A001477[n] = A063694[n]+a[n]

Sequence in context: A225869 A039972 A031124 * A081417 A133388 A282516

Adjacent sequences:  A063692 A063693 A063694 * A063696 A063697 A063698

KEYWORD

nonn

AUTHOR

Antti Karttunen, Aug 03 2001

STATUS

approved

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Last modified October 23 19:34 EDT 2018. Contains 316530 sequences. (Running on oeis4.)