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A074229
Numbers n such that Kronecker(6,n)==mu(gcd(6,n)).
2
1, 5, 19, 23, 25, 29, 43, 47, 49, 53, 67, 71, 73, 77, 91, 95, 97, 101, 115, 119, 121, 125, 139, 143, 145, 149, 163, 167, 169, 173, 187, 191, 193, 197, 211, 215, 217, 221, 235, 239, 241, 245, 259, 263, 265, 269, 283, 287, 289, 293, 307, 311, 313, 317, 331, 335
OFFSET
1,2
FORMULA
From Colin Barker, Dec 14 2015: (Start)
a(n) = (3/2+(3*i)/2)*(i^n-i*(-i)^n)-(-1)^n+6*(n+1)-9 where i = sqrt(-1).
a(n) = a(n-1) + a(n-4) - a(n-5) for n>5.
G.f.: x*(1+4*x+14*x^2+4*x^3+x^4) / ((1-x)^2*(1+x)*(1+x^2)).
(End)
PROG
(PARI) for (x=1, 200, for (y=1, 200, if (kronecker(x, y)==moebius(gcd(x, y)), write("km.txt", x, "; ", y, " : ", kronecker(x, y)))))
(PARI) isok(n) = kronecker(6, n) == moebius(gcd(6, n)); \\ Michel Marcus, Mar 17 2014
(PARI) Vec(x*(1+4*x+14*x^2+4*x^3+x^4)/((1-x)^2*(1+x)*(1+x^2)) + O(x^100)) \\ Colin Barker, Dec 14 2015
CROSSREFS
Equals 2 * A072065 + 1.
Sequence in context: A032731 A275954 A087840 * A152912 A191054 A097934
KEYWORD
nonn,easy
AUTHOR
Jon Perry, Sep 17 2002
EXTENSIONS
More terms from Michel Marcus, Mar 17 2014
STATUS
approved