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 A226782 If n=0 (mod 2) then a(n)=0, otherwise a(n)=4^(-1) in Z/nZ*. 7
 0, 0, 1, 0, 4, 0, 2, 0, 7, 0, 3, 0, 10, 0, 4, 0, 13, 0, 5, 0, 16, 0, 6, 0, 19, 0, 7, 0, 22, 0, 8, 0, 25, 0, 9, 0, 28, 0, 10, 0, 31, 0, 11, 0, 34, 0, 12, 0, 37, 0, 13, 0, 40, 0, 14, 0, 43, 0, 15, 0, 46, 0, 16, 0, 49, 0, 17 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 Index entries for linear recurrences with constant coefficients, signature (0,0,0,2,0,0,0,-1). FORMULA G.f.: -x^3*(x^6-4*x^2-1) / ( (x-1)^2*(1+x)^2*(x^2+1)^2 ). a(2n+1) = A225126(n+1). - Colin Barker, Jun 20 2013 MAPLE A226782 := proc(n)     local x , a, m;     a := 4 ;     m := 2 ;     if n mod m = 0 or n = 1 then         0;     else         msolve(x*a=1, n) ;         op(%) ;         op(2, %) ;     end if; end proc: # R. J. Mathar, Jun 28 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[4, n], {n, 1, 122}] PROG (PARI) a(n)=if(n%2, lift(Mod(1, n)/4), 0) \\ Charles R Greathouse IV, Jun 18 2013 CROSSREFS Cf. A092092, A226782-A226787. Sequence in context: A067565 A243154 A307717 * A010635 A272198 A272203 Adjacent sequences:  A226779 A226780 A226781 * A226783 A226784 A226785 KEYWORD nonn,easy AUTHOR José María Grau Ribas, Jun 18 2013 STATUS approved

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Last modified May 7 17:40 EDT 2021. Contains 343652 sequences. (Running on oeis4.)