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.

Showing 1-4 of 4 results.

A123583 Triangle read by rows: T(n, k) is the coefficient of x^k in the polynomial 1 - T_n(x)^2, where T_n(x) is the n-th Chebyshev polynomial of the first kind.

Original entry on oeis.org

0, 1, 0, -1, 0, 0, 4, 0, -4, 1, 0, -9, 0, 24, 0, -16, 0, 0, 16, 0, -80, 0, 128, 0, -64, 1, 0, -25, 0, 200, 0, -560, 0, 640, 0, -256, 0, 0, 36, 0, -420, 0, 1792, 0, -3456, 0, 3072, 0, -1024, 1, 0, -49, 0, 784, 0, -4704, 0, 13440, 0, -19712, 0, 14336, 0, -4096
Offset: 0

Views

Author

Gary W. Adamson and Roger L. Bagula, Nov 12 2006

Keywords

Comments

All row sum are zero. Row sums of absolute values are in A114619. - Klaus Brockhaus, May 29 2009

Examples

			First few rows of the triangle are:
  0;
  1, 0,  -1;
  0, 0,   4, 0,   -4;
  1, 0,  -9, 0,   24, 0,  -16;
  0, 0,  16, 0,  -80, 0,  128, 0,   -64;
  1, 0, -25, 0,  200, 0, -560, 0,   640, 0, -256;
  0, 0,  36, 0, -420, 0, 1792, 0, -3456, 0, 3072, 0, -1024;
First few polynomials (p(n, x) = 1 - T_{n}(x)^2) are:
  p(0, x) = 0,
  p(1, x) = 1 -    x^2,
  p(2, x) = 0    4*x^2 -   4*x^4,
  p(3, x) = 1 -  9*x^2 +  24*x^4 -   16*x^6,
  p(4, x) = 0   16*x^2 -  80*x^4 +  128*x^6 -   64*x^8,
  p(5, x) = 1 - 25*x^2 + 200*x^4 -  560*x^6 +  640*x^8 -  256*x^10,
  p(6, x) = 0   36*x^2 - 420*x^4 + 1792*x^6 - 3456*x^8 + 3072*x^10 - 1024*x^12.
		

Crossrefs

Programs

  • Magma
    [0] cat &cat[ Coefficients(1-ChebyshevT(n)^2): n in [1..8] ];
    
  • Mathematica
    (* First program *)
    Table[CoefficientList[1 - ChebyshevT[n, x]^2, x], {n, 0, 10}]//Flatten
    (* Second program *)
    T[n_, k_]:= T[n, k]= SeriesCoefficient[(1 -ChebyshevT[2*n,x])/2, {x,0,k}];
    Table[T[n, k], {n,0,12}, {k,0,2*n}]//Flatten (* G. C. Greubel, Jul 02 2021 *)
  • PARI
    v=[]; for(n=0, 8, v=concat(v, vector(2*n+1, j, polcoeff(1-poltchebi(n)^2, j-1)))); v
    
  • Sage
    def T(n): return ( (1 - chebyshev_T(2*n, x))/2 ).full_simplify().coefficients(sparse=False)
    flatten([T(n) for n in (0..12)]) # G. C. Greubel, Jul 02 2021

Formula

T(n, k) = coefficients of ( 1 - ChebyshevT(n, x)^2 ).
T(n, k) = coefficients of ( (1 - ChebyshevT(2*n, x))/2 ). - G. C. Greubel, Jul 02 2021

Extensions

Edited by N. J. A. Sloane, Mar 09 2008

A156645 Triangle T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = Product_{j=1..n} (1 - ChebyshevT(j, k+1)^2), b(n, 0) = n!, and m = 2, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 36, 1, 1, 1225, 1225, 1, 1, 41616, 1416100, 41616, 1, 1, 1413721, 1634261476, 1634261476, 1413721, 1, 1, 48024900, 1885939157025, 64069586905104, 1885939157025, 48024900, 1, 1, 1631432881, 2176372249076025, 2511659716192658889, 2511659716192658889, 2176372249076025, 1631432881, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 12 2009

Keywords

Examples

			Triangle begins as:
  1;
  1,        1;
  1,       36,             1;
  1,     1225,          1225,              1;
  1,    41616,       1416100,          41616,             1;
  1,  1413721,    1634261476,     1634261476,       1413721,        1;
  1, 48024900, 1885939157025, 64069586905104, 1885939157025, 48024900, 1;
		

Crossrefs

Cf. A007318 (m=0), A173585 (m=1), this sequence (m=2), A156646 (m=10).

Programs

  • Magma
    b:= func< n, k | n eq 0 select 1 else k eq 0 select Factorial(n) else (&*[1 - Evaluate(ChebyshevT(j), k+1)^2 : j in [1..n]]) >;
    T:= func< n,k,m | b(n,m)/(b(k,m)*b(n-k,m)) >;
    [T(n,k,2): k in [0..n], n in [0..12]]; // G. C. Greubel, Jul 03 2021
    
  • Mathematica
    (* First program *)
    b[n_, k_]:= b[n,k]= If[k==0, n!, Product[1 -ChebyshevT[j, k+1]^2, {j,n}]];
    T[n_, k_, m_]= b[n,m]/(b[k,m]*b[n-k,m]);
    Table[T[n, k, 2], {n,0,12}, {k,0,n}]//Flatten (* modified by G. C. Greubel, Jul 03 2021 *)
    (* Second program *)
    T[n_, k_, m_]:= T[n, k, m]= Product[(1 - ChebyshevT[2*j+2*k, m+1])/(1 - ChebyshevT[2*j, m+1]), {j, n-k}];
    Table[T[n,k,2], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Jul 03 2021 *)
  • Sage
    def b(n, k): return factorial(n) if (k==0) else product( 1 - chebyshev_T(j, k+1)^2 for j in (1..n) )
    def T(n, k, m): return b(n,m)/(b(k,m)*b(n-k,m))
    flatten([[T(n, k, 2) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Jul 03 2021

Formula

T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = Product_{j=1..n} (1 - ChebyshevT(j, k+1)^2), b(n, 0) = n!, and m = 2.
From G. C. Greubel, Jul 03 2021: (Start)
T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = (1/2^n)*Product_{j=1..n} (1 - ChebyshevT(2*j, k+1)), b(n, 0) = n!, and m = 2.
T(n, k, m) = Product_{j=1..n-k} ( (1 - ChebyshevT(2*j+2*k, m+1))/(1 - ChebyshevT(2*j, m+1)) ) with m = 2. (End)

Extensions

Edited by G. C. Greubel, Jul 03 2021

A156646 Triangle T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = Product_{j=1..n} (1 - ChebyshevT(j, k+1)^2), b(n, 0) = n!, and m = 10, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 484, 1, 1, 233289, 233289, 1, 1, 112444816, 54198633636, 112444816, 1, 1, 54198168025, 12591535188240100, 12591535188240100, 54198168025, 1, 1, 26123404543236, 2925290638056514680225, 1409984043580226203632400, 2925290638056514680225, 26123404543236, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 12 2009

Keywords

Examples

			Triangle begins as:
  1;
  1,           1;
  1,         484,                 1;
  1,      233289,            233289,                 1;
  1,   112444816,       54198633636,         112444816,           1;
  1, 54198168025, 12591535188240100, 12591535188240100, 54198168025, 1;
		

Crossrefs

Cf. A007318 (m=0), A173585 (m=1), A156645 (m=2), this sequence (m=10).

Programs

  • Magma
    b:= func< n, k | n eq 0 select 1 else k eq 0 select Factorial(n) else (&*[1 - Evaluate(ChebyshevT(j), k+1)^2 : j in [1..n]]) >;
    T:= func< n,k,m | b(n,m)/(b(k,m)*b(n-k,m)) >;
    [T(n,k,10): k in [0..n], n in [0..12]]; // G. C. Greubel, Jul 03 2021
    
  • Mathematica
    (* First program *)
    b[n_, k_]:= b[n,k]= If[k==0, n!, Product[1 -ChebyshevT[j, k+1]^2, {j,n}]];
    T[n_, k_, m_]= b[n,m]/(b[k,m]*b[n-k,m]);
    Table[T[n,k,10], {n,0,12}, {k,0,n}]//Flatten (* modified by G. C. Greubel, Jul 03 2021 *)
    (* Second program *)
    T[n_, k_, m_]:= T[n, k, m]= Product[(1 - ChebyshevT[2*j+2*k, m+1])/(1 - ChebyshevT[2*j, m+1]), {j, n-k}];
    Table[T[n,k,12], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Jul 03 2021 *)
  • Sage
    def b(n, k): return factorial(n) if (k==0) else product( 1 - chebyshev_T(j, k+1)^2 for j in (1..n) )
    def T(n, k, m): return b(n,m)/(b(k,m)*b(n-k,m))
    flatten([[T(n, k, 10) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Jul 03 2021

Formula

T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = Product_{j=1..n} (1 - ChebyshevT(j, k+1)^2), b(n, 0) = n!, and m = 10.
From G. C. Greubel, Jul 03 2021: (Start)
T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = (1/2^n)*Product_{j=1..n} (1 - ChebyshevT(2*j, k+1)), b(n, 0) = n!, and m = 10.
T(n, k, m) = Product_{j=1..n-k} ( (1 - ChebyshevT(2*j+2*k, m+1))/(1 - ChebyshevT(2*j, m+1)) ) with m = 10. (End)

Extensions

Edited by G. C. Greubel, Jul 03 2021

A173585 Triangle T(n, k, q) = c(n, q)/(c(k, q)*c(n-k, q)), where c(n, q) = Product_{j=1..n} t(2*j, q), t(n, q) = (1/4)*( (2 + sqrt(q))^n + (2 - sqrt(q))^n - 2 ), and q = 3, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 16, 1, 1, 225, 225, 1, 1, 3136, 44100, 3136, 1, 1, 43681, 8561476, 8561476, 43681, 1, 1, 608400, 1660970025, 23150231104, 1660970025, 608400, 1, 1, 8473921, 322220846025, 62555239000969, 62555239000969, 322220846025, 8473921, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 22 2010

Keywords

Examples

			Triangle begins as:
  1;
  1,      1;
  1,     16,          1;
  1,    225,        225,           1;
  1,   3136,      44100,        3136,          1;
  1,  43681,    8561476,     8561476,      43681,      1;
  1, 608400, 1660970025, 23150231104, 1660970025, 608400, 1;
		

Crossrefs

Cf. A022168 (q=0), A022173 (q=1), this sequence (q=3).
Cf. A007318 (m=0), this sequence (m=1), A156645 (m=2), A156646 (m=10).

Programs

  • Magma
    b:= func< n, k | n eq 0 select 1 else k eq 0 select Factorial(n) else (&*[1 - Evaluate(ChebyshevT(j), k+1)^2 : j in [1..n]]) >;
    T:= func< n,k,m | b(n,m)/(b(k,m)*b(n-k,m)) >;
    [T(n,k,1): k in [0..n], n in [0..12]]; // G. C. Greubel, Jul 06 2021
    
  • Mathematica
    (* First program *)
    f[n_, q_]:= (1/4)*((2+Sqrt[q])^n + (2-Sqrt[q])^n -2);
    c[n_, q_]:= Product[f[k, q], {k, 2, n, 2}]//Simplify;
    T[n_, k_, q_]:= c[n, q]/(c[k, q]*c[n - k, q]);
    Table[T[n, k, 3], {n, 0, 10, 2}, {k, 0, n, 2}]//Flatten (* modified by G. C. Greubel, Jul 06 2021 *)
    (* Second program *)
    t[n_, q_]:= (1/4)*(Round[(2+Sqrt[q])^n + (2-Sqrt[q])^n] -2);
    c[n_, q_]:= Product[t[2*j, q], {j,n}];
    T[n_, k_, q_]:= c[n, q]/(c[k, q]*c[n-k, q]);
    Table[T[n, k, 3], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Jul 06 2021 *)
  • Sage
    @CachedFunction
    def f(n,q): return (1/4)*( round((2 + sqrt(q))^n + (2 - sqrt(q))^n) - 2 )
    def c(n,q): return product( f(2*j, q) for j in (1..n))
    def T(n,k,q): return c(n, q)/(c(k, q)*c(n-k, q))
    flatten([[T(n,k,3) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Jul 06 2021

Formula

T(n, k, q) = c(n, q)/(c(k, q)*c(n-k, q)), where c(n, q) = Product_{j=1..n} t(2*j, q), t(n, q) = (1/4)*( (2 + sqrt(q))^n + (2 - sqrt(q))^n - 2 ), and q = 3.
From G. C. Greubel, Jul 06 2021: (Start)
T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = (1/2^n)*Product_{j=1..n} (1 - ChebyshevT(2*j, k+1)), b(n, 0) = n!, and m = 1.
T(n, k, m) = Product_{j=1..n-k} ( (1 - ChebyshevT(2*j+2*k, m+1))/(1 - ChebyshevT(2*j, m+1)) ) with m = 1. (End)

Extensions

Edited by G. C. Greubel, Jul 06 2021
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