

A226787


If n=0 (mod 3) then a(n)=0, otherwise a(n)=9^(1) in Z/nZ*.


7



0, 1, 0, 1, 4, 0, 4, 1, 0, 9, 5, 0, 3, 11, 0, 9, 2, 0, 17, 9, 0, 5, 18, 0, 14, 3, 0, 25, 13, 0, 7, 25, 0, 19, 4, 0, 33, 17, 0, 9, 32, 0, 24, 5, 0, 41, 21, 0, 11, 39, 0, 29, 6, 0, 49, 25, 0, 13, 46, 0, 34, 7, 0, 57, 29
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OFFSET

1,5


LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000


FORMULA

Empirical g.f.: x^2*(x^17x^143*x^12x^113*x^99*x^8x^64*x^54*x^3x^21) / (x^18 2*x^9 +1).  Colin Barker, Jun 20 2013


MATHEMATICA

Inv[a_, mod_] := Which[mod == 1, 0, GCD[a, mod] > 1, 0, True, Last@Reduce[a*x == 1, x, Modulus > mod]]; Table[Inv[9, n], {n, 1, 122}]


PROG

(PARI) a(n)=if(n%3, lift(Mod(1, n)/9), 0) \\ Charles R Greathouse IV, Jun 18 2013


CROSSREFS

Cf. A092092, A226782A226786.
Sequence in context: A137660 A123583 A236112 * A140574 A010636 A222302
Adjacent sequences: A226784 A226785 A226786 * A226788 A226789 A226790


KEYWORD

nonn,easy


AUTHOR

José María Grau Ribas, Jun 18 2013


STATUS

approved



