A353480 a(n) = 1 if n is an odd semiprime, otherwise 0.

0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Formula

a(n) = A000035(n) * A064911(n).

a(n) = A353477(n) + A353479(n).

a(n) = A064911(n) - A353478(n).

For all n <> 4, a(n) = A302048(n) + A353481(n).

Example

15 = 3*5 is an odd semiprime, thus a(15) = 1.
121 = 11*11 is an odd semiprime, thus a(121) = 1.

Prog

(PARI) A353480(n) = ((2==bigomega(n)) && (1==(n%2)));

Crossrefs

Characteristic function of A046315.

Cf. A000035, A064911, A302048, A353477, A353478, A353479, A353481.

Sequence in context: A025461 A169674 A324053 * A045698 A106197 A369048

Adjacent sequences: A353477 A353478 A353479 * A353481 A353482 A353483

Keyword

nonn

Author

Antti Karttunen, Apr 22 2022

Status

approved