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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.
5
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
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.
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
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 10 2024
STATUS
approved