OFFSET
1
COMMENTS
Completely additive modulo 3.
LINKS
PROG
(PARI)
A002110(n) = prod(i=1, n, prime(i));
A373153(n) = { my(f = factor(n), u); u=sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1))%3; if(2==u, -1, u); };
(PARI) A373153(n) = { my(u=(valuation(n, 2)-valuation(n, 3))%3); if(2==u, -1, u); }; \\ Antti Karttunen, Jun 01 2024
CROSSREFS
KEYWORD
sign
AUTHOR
Antti Karttunen, May 27 2024
STATUS
approved