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 A087292 Number of pairs of polynomials (f,g) in GF(3)[x] satisfying 1 <= deg(f) < =n, 1 <= deg(g) <= n and gcd(f,g) = 1. 3
 0, 24, 384, 4056, 38400, 351384, 3179904, 28671576, 258201600, 2324286744, 20919997824, 188284231896, 1694570841600, 15251175838104, 137260697334144, 1235346620381016, 11118120616550400, 100063088648317464, 900567807132948864, 8105110292090814936 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Unpublished result due to Stephen Suen, David desJardins and W. Edwin Clark. This is the case k = 2, q = 3 of their formula (q^(n+1)-q)^k*(1-1/(q^(k-1))) for the number of ordered k-tuples (f_1, ..., f_k) of polynomials in GF(q)[x] such that 1 <= deg(f_i) <= n for all i and gcd((f_1, ..., f_k) = 1. LINKS Index entries for linear recurrences with constant coefficients, signature (13,-39,27). FORMULA a(n) = 6*(3^n-1)^2. G.f.: -24*x*(3*x+1)/((x-1)*(3*x-1)*(9*x-1)). [Colin Barker, Sep 05 2012] EXAMPLE There are 6 polynomials in GF(3)[x] of degree 1. a(1) = 24 since the 6*4 = 24 ordered pairs (f,g) where g is not equal to f or 2f are the only ordered pairs of polynomials of degree 1 satisfying gcd(f,g) = 1. CROSSREFS Cf. A087289, A087290, A087291. Sequence in context: A025974 A059157 A228406 * A081138 A269181 A266185 Adjacent sequences:  A087289 A087290 A087291 * A087293 A087294 A087295 KEYWORD easy,nonn AUTHOR W. Edwin Clark, Aug 29 2003 STATUS approved

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Last modified December 3 21:17 EST 2021. Contains 349468 sequences. (Running on oeis4.)