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 A074232 Positive numbers that are not 3 or 6 (mod 9). 3
 1, 2, 4, 5, 7, 8, 9, 10, 11, 13, 14, 16, 17, 18, 19, 20, 22, 23, 25, 26, 27, 28, 29, 31, 32, 34, 35, 36, 37, 38, 40, 41, 43, 44, 45, 46, 47, 49, 50, 52, 53, 54, 55, 56, 58, 59, 61, 62, 63, 64, 65, 67, 68, 70, 71, 72, 73, 74, 76, 77, 79, 80, 81, 82, 83, 85, 86, 88, 89, 90, 91 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Previous name was: Numbers n such that Kronecker(9,n) = mu(gcd(9,n)). LINKS R. D. Carmichael, On the representation of numbers in the form x^3+y^3+z^3-3xyz, Bull. Amer. Math. Soc. 22 (1915), 111-117. Vladimir Shevelev, Representation of positive integers by the form x^3+y^3+z^3-3xyz, arXiv:1508.05748 [math.NT], 2015. Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,1,-1). FORMULA G.f.: x*(x^2-x+1)*(1+x+x^2)^2 / ( (x^6+x^5+x^4+x^3+x^2+x+1)*(x-1)^2 ). - R. J. Mathar, Apr 28 2016 MATHEMATICA Select[Range@ 91, ! Xor[Mod[#, 3] == 0, Mod[#, 9] == 0] &] (* or *) Select[Range@ 91, KroneckerSymbol[#, 9] == MoebiusMu[GCD[#, 9]] &] (* Michael De Vlieger, Sep 07 2015 *) PROG (PARI) lista(nn) = for (n=1, nn, if (kronecker(9, n)==moebius(gcd(9, n)) , print1(n, ", "))); \\ Michel Marcus, Aug 12 2015 (PARI) is(n)=valuation(n, 3)!=1 \\ Charles R Greathouse IV, Aug 12 2015 CROSSREFS Complement of A016051. Sequence in context: A039184 A039137 A071807 * A007417 A039099 A215069 Adjacent sequences:  A074229 A074230 A074231 * A074233 A074234 A074235 KEYWORD nonn,easy AUTHOR Jon Perry, Sep 17 2002 EXTENSIONS Offset corrected by Michel Marcus, Aug 12 2015 Definition edited by N. J. A. Sloane, Aug 25 2015 Better name from Vladimir Shevelev, Aug 12 2015 STATUS approved

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Last modified January 24 00:51 EST 2021. Contains 340398 sequences. (Running on oeis4.)