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A369975
Parity of A369974.
6
1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1
OFFSET
1
FORMULA
a(n) = A369974(n) mod 2 = A369978(n) mod 2.
a(n) <= A369001(n). [Because A369002 is a multiplicative semigroup; proof is similar to one given in A359780.]
PROG
(PARI)
A083345(n) = { my(f=factor(n)); numerator(vecsum(vector(#f~, i, f[i, 2]/f[i, 1]))); };
A369001(n) = !(A083345(n)%2);
memoA369974 = Map();
A369974(n) = if(1==n, 1, my(v); if(mapisdefined(memoA369974, n, &v), v, v = -sumdiv(n, d, if(d<n, A369001(n/d)*A369974(d), 0)); mapput(memoA369974, n, v); (v)));
A369975(n) = (A369974(n)%2);
CROSSREFS
Characteristic function of A369976.
Parity of A369974 and of A369978.
Differs from A369001 for the first time at n=81, where a(81) = 0, while A369001(81) = 1.
Cf. also A359780.
Sequence in context: A353557 A324917 A369974 * A369001 A361024 A354037
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 09 2024
STATUS
approved