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.

A342168 a(n) = U(n, (n+3)/2) where U(n, x) is a Chebyshev polynomial of the 2nd kind.

Original entry on oeis.org

1, 4, 24, 204, 2255, 30744, 499121, 9409960, 202176360, 4878316860, 130651068911, 3846719565780, 123517560398401, 4296240885694576, 160935647131239840, 6460088606857290384, 276655979838719058119, 12591439417867717440180, 606947064800948702246681
Offset: 0

Views

Author

Seiichi Manyama, Mar 03 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Table[ChebyshevU[n, (n + 3)/2], {n, 0, 18}] (* Amiram Eldar, Apr 27 2021 *)
  • PARI
    a(n) = polchebyshev(n, 2, (n+3)/2);
    
  • PARI
    a(n) = sum(k=0, n, (n+1)^(n-k)*binomial(2*n+1-k, k));
    
  • PARI
    a(n) = sum(k=0, n, (n+1)^k*binomial(n+1+k, 2*k+1));

Formula

a(n) = Sum_{k=0..n} (n+1)^(n-k) * binomial(2*n+1-k,k) = Sum_{k=0..n} (n+1)^k * binomial(n+1+k,2*k+1).
a(n) ~ exp(3) * n^n. - Vaclav Kotesovec, May 06 2021

A107995 Chebyshev polynomial of the second kind U[n,x] evaluated at x=n+2.

Original entry on oeis.org

1, 6, 63, 980, 20305, 526890, 16451071, 600940872, 25154396001, 1187422368110, 62418042417599, 3616337930622300, 228977061309711793, 15731733543660288210, 1165677769357309014015, 92665403695822344828176
Offset: 0

Views

Author

Roger L. Bagula, Mar 01 2006

Keywords

Examples

			a(3)=980 because U[3,x]=8x^3-4x and U[3,5]=8*5^3-4*5=980.
		

References

  • Rosenblum and Rovnyak, Hardy Classes and Operator Theory,Dover, New York,1985, page 18.
  • G. Szego, Orthogonal polynomials, Amer. Math. Soc., Providence, 1939, p. 29.
  • G. Freud, Orthogonal Polynomials, Pergamon Press, Oxford, 1966, p. 35.

Crossrefs

Programs

  • Maple
    with(orthopoly): seq(U(n,n+2),n=0..17);
  • Mathematica
    Table[ChebyshevU[n, n + 2], {n, 0, 15}] (* Amiram Eldar, Mar 05 2021 *)
  • PARI
    a(n) = polchebyshev(n, 2, n+2); \\ Seiichi Manyama, Mar 05 2021
    
  • PARI
    a(n) = sum(k=0, n, (2*n+2)^k*binomial(n+1+k, 2*k+1)); \\ Seiichi Manyama, Mar 05 2021

Formula

a(n) = Sum_{k=0..n} (2*n+2)^(n-k) * binomial(2*n+1-k,k) = Sum_{k=0..n} (2*n+2)^k * binomial(n+1+k,2*k+1). - Seiichi Manyama, Mar 05 2021
a(n) ~ exp(2) * 2^n * n^n. - Vaclav Kotesovec, Mar 05 2021

Extensions

Edited by N. J. A. Sloane, Apr 05 2006

A343261 a(n) = 2 * T(n,(n+2)/2) where T(n,x) is a Chebyshev polynomial of the first kind.

Original entry on oeis.org

2, 3, 14, 110, 1154, 15127, 238142, 4379769, 92198402, 2186871698, 57721023502, 1678243366813, 53301709843202, 1836220544383695, 68200709735854334, 2716906424134261502, 115561578124838522882, 5227260815326346060059, 250566480717349417632398
Offset: 0

Views

Author

Seiichi Manyama, Apr 09 2021

Keywords

Crossrefs

Main diagonal of A299741.

Programs

  • Mathematica
    Table[2*ChebyshevT[n, (n+2)/2], {n, 0, 18}] (* Amiram Eldar, Apr 09 2021 *)
  • PARI
    a(n) = 2*polchebyshev(n, 1, (n+2)/2);
    
  • PARI
    a(n) = round(2*cos(n*acos((n+2)/2)));
    
  • PARI
    a(n) = if(n==0, 2, 2*n*sum(k=0, n, n^k*binomial(n+k, 2*k)/(n+k)));

Formula

a(n) = 2 * cos(n*arccos((n+2)/2)).
a(n) = 2 * n * Sum_{k=0..n} n^k * binomial(n+k,2*k)/(n+k) for n > 0.
a(n) ~ exp(2) * n^n. - Vaclav Kotesovec, Apr 09 2021

A372817 Table read by antidiagonals: T(m,n) = number of 1-metered (m,n)-parking functions.

Original entry on oeis.org

1, 0, 2, 0, 3, 3, 0, 4, 8, 4, 0, 6, 21, 15, 5, 0, 8, 55, 56, 24, 6, 0, 12, 145, 209, 115, 35, 7, 0, 16, 380, 780, 551, 204, 48, 8, 0, 24, 1000, 2912, 2640, 1189, 329, 63, 9, 0, 32, 2625, 10868, 12649, 6930, 2255, 496, 80, 10, 0, 48, 6900, 40569, 60606, 40391, 15456, 3905, 711, 99, 11
Offset: 1

Views

Author

Spencer Daugherty, May 13 2024

Keywords

Examples

			For T(3,2) the 1-metered (3,2)-parking functions are 111, 121, 211, 212.
Table begins:
  1,  2,    3,     4,     5,      6,      7, ...
  0,  3,    8,    15,    24,     35,     48, ...
  0,  4,   21,    56,   115,    204,    329, ...
  0,  6,   55,   209,   551,   1189,   2255, ...
  0,  8,  145,   780,  2640,   6930,  15456, ...
  0, 12,  380,  2912, 12649,  40391, 105937, ...
  0, 16, 1000, 10868, 60606, 235416, 726103, ...
  ...
		

Crossrefs

Main diagonal is A097690 and first row of A372816.
First, second, and third diagonals above main are A097691, A342167, A342168.
Second column A029744. Second row A005563. Third row A242135.

Formula

T(m,n) = (n*(n+sqrt(n^2 - 4))-2)/(n*(n+sqrt(n^2 - 4))-4)*((n+sqrt(n^2-4))/2)^m + (n*(n-sqrt(n^2 - 4))-2)/(n*(n-sqrt(n^2 - 4))-4)*((n-sqrt(n^2-4))/2)^m.
T(m,n) = n*T(m-1,n) - T(m-2,n) with T(0,n) = 1.
Showing 1-4 of 4 results.