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.

A097784 Partial sums of Chebyshev sequence S(n,10) = U(n,5) = A004189(n+1).

Original entry on oeis.org

1, 11, 110, 1090, 10791, 106821, 1057420, 10467380, 103616381, 1025696431, 10153347930, 100507782870, 994924480771, 9848737024841, 97492445767640, 965075720651560, 9553264760747961, 94567571886828051, 936122454107532550, 9266656969188497450
Offset: 0

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Author

Wolfdieter Lang, Aug 31 2004

Keywords

Crossrefs

Cf. A098296.
Cf. A212336 for more sequences with g.f. of the type 1/(1-k*x+k*x^2-x^3).

Programs

  • GAP
    a:=[1,11,110];; for n in [4..30] do a[n]:=11*a[n-1]-11*a[n-2]+ a[n-3]; od; a; # G. C. Greubel, May 24 2019
  • Magma
    I:=[1,11,110]; [n le 3 select I[n] else 11*Self(n-1)-11*Self(n-2) +Self(n-3): n in [1..30]]; // G. C. Greubel, May 24 2019
    
  • Mathematica
    LinearRecurrence[{11,-11,1}, {1,11,110}, 30] (* G. C. Greubel, May 24 2019 *)
    CoefficientList[Series[1/(1-11x+11x^2-x^3),{x,0,30}],x] (* Harvey P. Dale, Aug 24 2021 *)
  • PARI
    Vec(1/((1-x)*(1-10*x+x^2)) + O(x^30)) \\ Colin Barker, Jun 14 2015
    
  • Sage
    (1/((1-x)*(1 - 10*x + x^2))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 24 2019
    

Formula

a(n) = Sum_{k=0..n} S(k, 10) with S(k, 10) = U(k, 5) = A004189(k+1) Chebyshev's polynomials of the second kind.
G.f.: 1/((1-x)*(1 - 10*x + x^2)) = 1/(1 - 11*x + 11*x^2 - x^3).
a(n) = 11*a(n-1) - 11*a(n-2) + a(n-3) with n >= 2, a(-1)=0, a(0)=1, a(1)=11.
a(n) = 10*a(n-1) - a(n-2) + 1 with n >= 1, a(-1)=0, a(0)=1.
a(n) = (S(n+1, 10) - S(n, 10) - 1)/8.
a(n) = (-6 + (27-11*sqrt(6))*(5 - 2*sqrt(6))^n + (5 + 2*sqrt(6))^n*(27 + 11*sqrt(6)))/48. - Colin Barker, Mar 05 2016