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 A077248 Combined Diophantine Chebyshev sequences A077246 and A077244. 3

%I

%S 2,3,13,22,102,173,803,1362,6322,10723,49773,84422,391862,664653,

%T 3085123,5232802,24289122,41197763,191227853,324349302,1505533702,

%U 2553596653,11853041763,20104423922,93318800402

%N Combined Diophantine Chebyshev sequences A077246 and A077244.

%C 3*a(n)^2 - 5*b(n)^2 = 7, with the companion sequence b(n)= A077247(n).

%C Positive values of x (or y) satisfying x^2 - 8xy + y^2 + 35 = 0. - _Colin Barker_, Feb 08 2014

%H Vincenzo Librandi, <a href="/A077248/b077248.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Ch#Cheby">Index entries for sequences related to Chebyshev polynomials.</a>

%F a(2*k)= A077246(k) and a(2*k+1)= A077244(k), k>=0.

%F G.f.: (1-x)*(2+x)*(1+2*x)/(1-8*x^2+x^4).

%e 13 = a(2) = sqrt((5*A077247(2)^2 + 7)/3) = sqrt((5*10^2 + 7)/3)= sqrt(169) = 13.

%t CoefficientList[Series[(1 - x) (2 + x) (1 + 2 x)/(1 - 8 x^2 + x^4), {x, 0, 30}], x] (* _Vincenzo Librandi_, Feb 11 2014 *)

%K nonn,easy

%O 0,1

%A _Wolfdieter Lang_, Nov 08 2002

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Last modified January 27 09:09 EST 2020. Contains 331293 sequences. (Running on oeis4.)