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 A112132 Period 4: repeat [1, 3, 1, 7]. 2
 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Terms of the simple continued fraction of 10/(3*sqrt(205)-35). Decimal expansion of 4390/3333. [Paolo P. Lava, Aug 05 2009] LINKS Index entries for linear recurrences with constant coefficients, signature (0,0,0,1). FORMULA a(n) = 2*(n mod 4)-[(n+1) mod 4]+[(n+2) mod 4]. - Paolo P. Lava, Aug 29 2007 a(n) = 3+I*I^(n-1)+2*(-1)^n-I*(-I)^(n-1). - Paolo P. Lava, Jul 17 2008 a(n+1) = 3-2*sin(Pi*n/2)-2*(-1)^n. - R. J. Mathar, Oct 08 2011 Multiplicative with a(2) = 3, a(2^e) = 7 if e = 2, a(p^e) = 1 otherwise. - Antti Karttunen, Mar 31 2013 From Wesley Ivan Hurt, Jul 09 2016: (Start) G.f.: x*(1+3*x+x^2+7*x^3)/(1-x^4). a(n) = a(n-4) for n>3. a(2n) = 5+2*(-1)^n, a(2n-1) = 1. (End) MAPLE seq(op([1, 3, 1, 7]), n=1..50); # Wesley Ivan Hurt, Jul 09 2016 MATHEMATICA PadRight[{}, 100, {1, 3, 1, 7}] (* Wesley Ivan Hurt, Jul 09 2016 *) PROG (PARI) a(n)=1+2*((n-1)%2)*((n-1)%4); \\ Jaume Oliver Lafont, Aug 28 2009; corrected by Antti Karttunen, Mar 31 2013 (PARI) a(n)=[1, 3, 1, 7][1+(n-1)%4]; \\ Joerg Arndt, Apr 02 2013 (MAGMA) &cat [[1, 3, 1, 7]^^30]; // Wesley Ivan Hurt, Jul 09 2016 CROSSREFS First differences of A112062. Also half of the first differences of A112072. Cf. A112086. Sequence in context: A136011 A227984 A021991 * A053381 A038712 A065745 Adjacent sequences:  A112129 A112130 A112131 * A112133 A112134 A112135 KEYWORD nonn,mult,easy AUTHOR Antti Karttunen, Aug 28 2005 STATUS approved

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Last modified April 7 13:36 EDT 2020. Contains 333305 sequences. (Running on oeis4.)