A089224 - OEIS

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A089224

In binary representation: number of zeros of number of zeros of n.

2

0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 2, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 2, 2, 0, 2, 0, 0, 1, 2, 0, 0, 1, 0, 1, 1, 0, 2, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 2, 1, 2, 2, 0, 1, 2, 2, 0, 2, 0, 0, 1, 1, 2, 2, 0, 2, 0, 0, 1, 2, 0, 0, 1, 0, 1, 1, 0, 1, 2, 2, 0, 2, 0

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,17

LINKS

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

Index entries for sequences related to binary expansion of n.

FORMULA

a(n) = A023416(A023416(n)).

EXAMPLE

a(0) = 0; a(1) = 1; a(16) = 2; a(256) = 3; a(65536) = 4.

MAPLE

a:= n-> (z-> z(z(n)))(k-> `if`(k=0, 1, add(1-i, i=Bits[Split](k)))):

seq(a(n), n=0..100); # Alois P. Heinz, Jul 04 2022

MATHEMATICA

a[n_] := DigitCount[DigitCount[n, 2, 0], 2, 0]; Array[a, 100, 0] (* Amiram Eldar, Jul 24 2023 *)

PROG

(Haskell)

a089224 = a023416 . a023416 -- Reinhard Zumkeller, Mar 31 2015

(Python)

def a(n): return bin(bin(n)[2:].count("0"))[2:].count("0")

print([a(n) for n in range(102)]) # Michael S. Branicky, Jul 04 2022

CROSSREFS

Cf. A054868, A007088.

Sequence in context: A274472 A283669 A220945 * A344987 A359325 A325122

Adjacent sequences: A089221 A089222 A089223 * A089225 A089226 A089227

KEYWORD

nonn,base

AUTHOR

Reinhard Zumkeller, Dec 10 2003

STATUS

approved