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 A047389 Numbers that are congruent to {3, 5} mod 7. 5
 3, 5, 10, 12, 17, 19, 24, 26, 31, 33, 38, 40, 45, 47, 52, 54, 59, 61, 66, 68, 73, 75, 80, 82, 87, 89, 94, 96, 101, 103, 108, 110, 115, 117, 122, 124, 129, 131, 136, 138, 143, 145, 150, 152, 157, 159, 164, 166, 171 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primitive roots of 7. The first differences are periodic: 2,5,2,5,2,5,.... - Paolo P. Lava, Feb 29 2008 LINKS Index entries for linear recurrences with constant coefficients, signature (1,1,-1). FORMULA a(n) = -4 + (1/2)*Sum_{k=0..n} (7 - 3*(-1)^n), with n >= 1. - Paolo P. Lava, Feb 29 2008 a(n) = 7*n - a(n-1) - 6, n > 1. - Vincenzo Librandi, Aug 05 2010 From Bruno Berselli, Sep 08 2010: (Start) G.f.: x*(3 + 2*x + 2*x^2)/((1+x)*(1-x)^2). a(n) - a(n-1) - a(n-2) + a(n-3) = 0 for n > 3. a(n) = (14*n - 5 - 3*(-1)^n)/4. (End) MAPLE P:=proc(n, m) local a, i, ok; for i from 1 by 1 to n do if (i^(m-1) mod m)=1 then a:=1; ok:=1; while a

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Last modified July 30 03:08 EDT 2021. Contains 346347 sequences. (Running on oeis4.)