A326140 a(n) = gcd(A318878(n), A318879(n)).

1, 1, 2, 1, 4, 2, 6, 1, 5, 2, 10, 2, 12, 2, 6, 1, 16, 1, 18, 2, 10, 2, 22, 2, 19, 2, 14, 6, 28, 6, 30, 1, 18, 2, 22, 1, 36, 2, 22, 2, 40, 2, 42, 2, 12, 2, 46, 2, 41, 1, 30, 6, 52, 2, 38, 2, 34, 2, 58, 6, 60, 2, 22, 1, 46, 6, 66, 2, 42, 2, 70, 1, 72, 2, 26, 6, 58, 2, 78, 2, 41, 2, 82, 2, 62, 2, 54, 2, 88, 6, 70, 2, 58, 2

Offset

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Prog

(PARI) A326140(n) = { my(t=0, u=0); fordiv(n, d, d -= 2*eulerphi(d); if(d<0, t -= d, u += d)); gcd(t, u); };
(PARI)
A318878(n) = sumdiv(n, d, d=(2*eulerphi(d))-d; (d>0)*d);
A318879(n) = sumdiv(n, d, d=d-(2*eulerphi(d)); (d>0)*d);
A326140(n) = gcd(A318878(n), A318879(n));

Crossrefs

Cf. A033879, A083254, A318878, A318879, A326141.

Cf. also A009194, A325385, A325813, A325975, A326046, A326047, A326048, A326056, A326057, A326060, A326062, A326129, A326130, A326144.

Sequence in context: A345046 A125131 A003958 * A082729 A326069 A326068

Adjacent sequences: A326137 A326138 A326139 * A326141 A326142 A326143

Keyword

nonn

Author

Antti Karttunen, Jun 09 2019

Status

approved