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 1-3 of 3 results.

A117715 Triangle, read by rows, T(n, k) = Fibonacci(n, k), where Fibonacci(n, x) is the Fibonacci polynomial.

Original entry on oeis.org

0, 1, 1, 0, 1, 2, 1, 2, 5, 10, 0, 3, 12, 33, 72, 1, 5, 29, 109, 305, 701, 0, 8, 70, 360, 1292, 3640, 8658, 1, 13, 169, 1189, 5473, 18901, 53353, 129949, 0, 21, 408, 3927, 23184, 98145, 328776, 927843, 2298912, 1, 34, 985, 12970, 98209, 509626, 2026009, 6624850, 18674305, 46866034
Offset: 0

Views

Author

Roger L. Bagula, Apr 13 2006

Keywords

Examples

			Triangle begins as:
  0;
  1,  1;
  0,  1,   2;
  1,  2,   5,   10;
  0,  3,  12,   33,   72;
  1,  5,  29,  109,  305,   701;
  0,  8,  70,  360, 1292,  3640,  8658;
  1, 13, 169, 1189, 5473, 18901, 53353, 129949;
		

References

  • Steven Wolfram, The Mathematica Book, Cambridge University Press, 3rd ed. 1996, page 728

Crossrefs

Cf. A000045, A117716, A049310, A073133, A157103 (antidiagonals).
Main diagonal and first lower diagonal give: A084844, A084845.
Cf. A352361.

Programs

  • Magma
    A117715:= func< n, k | k eq 0 select (n mod 2) else Evaluate(DicksonSecond(n-1, -1), k) >;
    [A117715(n, k): k in [0..n], n in [0..13]]; // G. C. Greubel, Oct 01 2024
    
  • Maple
    with(combinat):for n from 0 to 9 do seq(fibonacci(n,m), m = 0 .. n) od; # Zerinvary Lajos, Apr 09 2008
  • Mathematica
    Table[Fibonacci[n, k], {n,0,12}, {k,0,n}]//Flatten
  • Python
    from sympy import fibonacci
    def T(n, m): return 0 if n==0 else fibonacci(n, m)
    for n in range(21): print([T(n, m) for m in range(n + 1)]) # Indranil Ghosh, Aug 12 2017
    
  • SageMath
    def A117715(n,k): return lucas_number1(n, k, -1)
    flatten([[A117715(n,k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Oct 01 2024

Formula

T(n, 1) = A000045(n).
T(n, 3) = A006190(n).
T(n, 4) = A001076(n).
T(n, 5) = A052918(n-1).
T(5, k) = A057721(k).
T(6, k) = A124152(k).
T(n, k) = (-1)^(n-1)*A352361(n-k, n). - G. C. Greubel, Oct 01 2024

Extensions

Definition simplified by the Assoc. Editors of the OEIS, Nov 17 2009

A117724 Triangle T(n,k) = coefficient [x^n] of x^2/(1-(k+1)*x^2-x^3) for row n, and columns k = 0..n, read by rows.

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 2, 3, 4, 5, 1, 1, 1, 1, 1, 1, 1, 4, 9, 16, 25, 36, 49, 2, 4, 6, 8, 10, 12, 14, 16, 2, 9, 28, 65, 126, 217, 344, 513, 730, 3, 12, 27, 48, 75, 108, 147, 192, 243, 300, 4, 22, 90, 268, 640, 1314, 2422, 4120, 6588, 10030, 14674
Offset: 0

Views

Author

Roger L. Bagula, Apr 13 2006

Keywords

Examples

			The table starts:
  0;
  0,  0;
  1,  1,  1;
  0,  0,  0,  0;
  1,  2,  3,  4,   5;
  1,  1,  1,  1,   1,   1;
  1,  4,  9, 16,  25,  36,  49;
  2,  4,  6,  8,  10,  12,  14,  16;
  2,  9, 28, 65, 126, 217, 344, 513, 730;
  3, 12, 27, 48,  75, 108, 147, 192, 243, 300;
		

Crossrefs

Programs

  • Magma
    m:=12;
    R:=PowerSeriesRing(Integers(), m+2);
    A117724:= func< n, k | Coefficient(R!( x^2/(1-(k+1)*x^2-x^3) ), n) >;
    [A117724(n, k): k in [0..n], n in [0..m]]; // G. C. Greubel, Jul 23 2023
    
  • Maple
    t:=taylor(x^2/(1-(k+1)*x^2-x^3), x, 15):
    seq(seq(coeff(t,x,n), k=0..n),n=0..12); # Nathaniel Johnston, Apr 27 2011
  • Mathematica
    T[n_, k_]:= T[n, k]= Coefficient[Series[x^2/(1-(k+1)*x^2-x^3), {x,0,n+ 2}], x, n];
    Table[T[n,k], {n,0,12}, {k,0,n}]//Flatten
  • SageMath
    def A117724(n, k):
        P. = PowerSeriesRing(QQ)
        return P( x^2/(1-(k+1)*x^2-x^3) ).list()[n]
    flatten([[A117724(n, k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Jul 23 2023

Formula

T(n,k) = coefficient [x^n] ( x^2/(1-(k+1)*x^2-x^3) ).
T(n, 0) = A000931(n+1).
T(n, 1) = A008346(n-2) = (-1)^(n-1)*A119282(n-1).
T(n, 2) = A052931(n-2).

Extensions

Sign in definition corrected, offset set to -1 by Assoc. Eds. of the OEIS, Jun 15 2010
Edited by G. C. Greubel, Jul 23 2023

A368892 a(n) = Sum_{k=0..floor(n/3)} n^(n-3*k) * binomial(n-2*k,k).

Original entry on oeis.org

1, 1, 4, 28, 264, 3200, 47521, 835569, 16974208, 391147867, 10080150040, 287244283821, 8967781893889, 304393809948904, 11160668048222588, 439582708115133751, 18509867068477014112, 829768603643818659302, 39454459640462073466945
Offset: 0

Views

Author

Seiichi Manyama, Jan 09 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[n^n * HypergeometricPFQ[{1/3 - n/3, 2/3 - n/3, -n/3}, {1/2 - n/2, -n/2}, -27/(4*n^3)], {n, 1, 20}]] (* Vaclav Kotesovec, Jan 09 2024 *)
  • PARI
    a(n) = sum(k=0, n\3, n^(n-3*k)*binomial(n-2*k, k));

Formula

a(n) = [x^n] 1/(1 - n*x - x^3).
a(n) ~ n^n. - Vaclav Kotesovec, Jan 09 2024
Showing 1-3 of 3 results.