A373588 a(n) = 1 if the number of prime factors (with multiplicity) of n is a multiple of 3, and all of them are of the type 3m-1 (in A003627), otherwise 0.

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

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..100000

Index entries for characteristic functions

Prog

(PARI) A373588(n) = if(bigomega(n)%3, 0, my(f = factor(n)); for(i = 1, #f~, if((f[i, 1]%3) != 2, return(0))); (1));

Crossrefs

Characteristic function of A373589.

Cf. A001222, A003627, A004612, A145784.

Differs from A373491 for the first time at n=343, where a(343) = 0, while A373491(343) = 1.

Sequence in context: A015920 A014744 A373491 * A373596 A373472 A373493

Adjacent sequences: A373585 A373586 A373587 * A373589 A373590 A373591

Keyword

nonn

Author

Antti Karttunen, Jun 10 2024

Status

approved