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 A131028 Periodic sequence (7, 4, 1, 1, 4, 7). 10
 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Fourth column of triangular array T defined in A131022. a(n) = A084104(n+3). Continued fractions of (131 + sqrt(18530))/37 = 7.2195930... - R. J. Mathar, Mar 08 2012 LINKS Index entries for linear recurrences with constant coefficients, signature (2,-2,1). FORMULA a(1) = a(6) = 7, a(2) = a(5) = 4, a(3) = a(4) = 1; for n > 6, a(n) = a(n-6). G.f.: (7-10*x+7*x^2)/((1-x)*(1-x+x^2)). a(n) = 1/30*(8*(n mod 6) - 7*((n+1) mod 6) - 7*((n+2) mod 6) + 8*((n+3) mod 6) + 23*((n+4) mod 6) + 23*((n+5) mod 6)), with n>=0. - Paolo P. Lava, Jun 19 2007 a(n) = 4+2*sqrt(3)*cos(Pi/6*(2*n-1)). - Werner Schulte, Jul 21 2017 MATHEMATICA PadRight[{}, 120, {7, 4, 1, 1, 4, 7}] (* Harvey P. Dale, Jul 15 2013 *) PROG (PARI) {m=105; for(n=1, m, r=(n-1)%6; print1(if(r==0||r==5, 7, if(r==1||r==4, 4, 1)), ", "))} (MAGMA) m:=105; [ [7, 4, 1, 1, 4, 7][(n-1) mod 6 + 1]: n in [1..m] ]; CROSSREFS Cf. A131022, A084104. Other columns of T are in A088911, A131026, A131027, A131029, A131030. Sequence in context: A082665 A011101 A021935 * A225463 A010138 A199157 Adjacent sequences:  A131025 A131026 A131027 * A131029 A131030 A131031 KEYWORD nonn,easy AUTHOR Klaus Brockhaus, following a suggestion of Paul Curtz, Jun 10 2007 STATUS approved

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Last modified September 19 07:24 EDT 2020. Contains 337178 sequences. (Running on oeis4.)