A102391 Evil numbers in evil places.

0, 0, 0, 3, 0, 5, 6, 0, 0, 9, 10, 0, 12, 0, 0, 15, 0, 17, 18, 0, 20, 0, 0, 23, 24, 0, 0, 27, 0, 29, 30, 0, 0, 33, 34, 0, 36, 0, 0, 39, 40, 0, 0, 43, 0, 45, 46, 0, 48, 0, 0, 51, 0, 53, 54, 0, 0, 57, 58, 0, 60, 0, 0, 63, 0, 65, 66, 0, 68, 0, 0, 71, 72, 0, 0, 75, 0, 77, 78, 0, 80, 0, 0, 83, 0, 85

Offset

0,4

Comments

Evil numbers A001969(n) appear at positions indexed by the evil numbers, 0 otherwise. A001477(n) = A102391(n) + A102392(n).

Links

Table of n, a(n) for n=0..85.

Formula

a(n) = if((1+floor(n/2)) (1+(-1)^A000120(n))/2 = 0, 0, n).

a(n) = if((1+floor(n/2)) (1+(-1)^A010060(n))/2 = 0, 0, n).

Mathematica

a[n_] := If[EvenQ @ DigitCount[n, 2, 1], n, 0]; Array[a, 100, 0] (* Amiram Eldar, Aug 02 2020 *)

Prog

(Python)
def A102391(n): return 0 if n.bit_count()&1 else n # Chai Wah Wu, Nov 23 2023

Crossrefs

Cf. A000120, A001477, A001969, A010060, A102391, A102392.

Sequence in context: A351692 A181840 A198432 * A038556 A342303 A193508

Adjacent sequences: A102388 A102389 A102390 * A102392 A102393 A102394

Keyword

easy,nonn,base

Author

Paul Barry, Jan 06 2005

Status

approved