A089224 In binary representation: number of zeros of number of zeros of n.

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

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.

Cf. A023416.

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