cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A077248 Combined Diophantine Chebyshev sequences A077246 and A077244.

Original entry on oeis.org

2, 3, 13, 22, 102, 173, 803, 1362, 6322, 10723, 49773, 84422, 391862, 664653, 3085123, 5232802, 24289122, 41197763, 191227853, 324349302, 1505533702, 2553596653, 11853041763, 20104423922, 93318800402
Offset: 0

Views

Author

Wolfdieter Lang, Nov 08 2002

Keywords

Comments

3*a(n)^2 - 5*b(n)^2 = 7, with the companion sequence b(n)= A077247(n).
Positive values of x (or y) satisfying x^2 - 8xy + y^2 + 35 = 0. - Colin Barker, Feb 08 2014

Examples

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

Links

Programs

  • Mathematica
    CoefficientList[Series[(1 - x) (2 + x) (1 + 2 x)/(1 - 8 x^2 + x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Feb 11 2014 *)

Formula

a(2*k)= A077246(k) and a(2*k+1)= A077244(k), k>=0.
G.f.: (1-x)*(2+x)*(1+2*x)/(1-8*x^2+x^4).
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