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A070414
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a(n) = 7^n mod 30.
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1
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1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = a(n-1) - a(n-2) + a(n-3).
G.f.: ( -1-6*x-13*x^2 ) / ( (x-1)*(1+x^2) ). (End)
a(n) = a(n-4).
E.g.f.: 10*exp(x) - 9*cos(x) - 3*sin(x). (End)
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MATHEMATICA
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LinearRecurrence[{1, -1, 1}, {1, 7, 19}, 90] (* or *) PadRight[{}, 90, {1, 7, 19, 13}] (* Harvey P. Dale, Aug 09 2020 *)
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PROG
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(Sage) [power_mod(7, n, 30) for n in range(0, 84)] # Zerinvary Lajos, Nov 27 2009
(PARI) a(n) = lift(Mod(7, 30)^n); \\ Altug Alkan, Mar 20 2016
(Magma) [Modexp(7, n, 30): n in [0..100]]; // Bruno Berselli, Mar 22 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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