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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A171731 Triangle T : T(n,k)= binomial(n,k)*Fibonacci(n-k)= A007318(n,k)*A000045(n-k).

Original entry on oeis.org

0, 1, 0, 1, 2, 0, 2, 3, 3, 0, 3, 8, 6, 4, 0, 5, 15, 20, 10, 5, 0, 8, 30, 45, 40, 15, 6, 0, 13, 56, 105, 105, 70, 21, 7, 0, 21, 104, 224, 280, 210, 112, 28, 8, 0, 34, 189, 468, 672, 630, 378, 168, 36, 9, 0, 55, 340, 945, 1560, 1680, 1260, 630, 240, 45, 10, 0
Offset: 0

Views

Author

Philippe Deléham, Dec 16 2009

Keywords

Comments

Diagonal sums : A112576.
Essentially the same as A094440. - Peter Bala, Jan 06 2015

Examples

			Triangle begins :
0 ;
1,0 ;
1,2,0 ;
2,3,3,0 ;
3,8,6,4,0 ;
5,15,20,10,5,0 ;
...
		

Crossrefs

Programs

  • Mathematica
    Flatten[Table[Binomial[n,k]Fibonacci[n-k],{n,0,10},{k,0,n}]] (* Harvey P. Dale, Jan 16 2013 *)

Formula

Sum_{k, 0<=k<=n} T(n,k)*x^k = A000045(n), A001906(n), A093131(n), A099453(n-1), A081574(n), A081575(n) for x = 0,1,2,3,4,5 respectively. Sum_{k, 0<=k<=n} T(n,k)*2^(n-k) = A014445(n).

A363826 Triangular array, read by rows: T(n,k) = coefficients of the polynomial (-1)^(n+1)/(n+1)! N(x), where N(x) is the numerator of the (n-1)st derivative of 1/(1-x-x^2), for k = 1..n.

Original entry on oeis.org

1, 1, 2, 2, 3, 3, 3, 8, 6, 4, 1, 3, 4, 2, 1, 8, 30, 45, 40, 15, 6, 13, 56, 105, 105, 70, 21, 7, 21, 104, 224, 280, 210, 112, 28, 8, 34, 189, 468, 672, 630, 378, 168, 36, 9, 11, 68, 189, 312, 336, 252, 126, 48, 9, 2, 89, 605, 1870, 3465, 4290, 3696, 2310, 990
Offset: 1

Views

Author

Clark Kimberling, Nov 26 2023

Keywords

Comments

The polynomials N(x) form a strong divisibility sequence. Multiplying every 5th polynomial by 5 results in another strong divisibility sequence of polynomials, F(n,x), in a Comment in A094440.

Examples

			First eleven rows:
   1
   1    2
   2    3    3
   3    8    6    4
   1    3    4    2    1
   8   30   45   40   15    6
  13   56  105  105   70   21    7
  21  104  224  280  210  112   28   8
  34  189  468  672  630  378  168  36   9
  11   68  189  312  336  252  126  48   9  2
  89  605 1870 3465 4290 3696 2310 990 330 55 11
Row 3 represents the polynomial 2 + 3*x + 3*x^2, extracted from
f"(x) = -((2*(2 + 3*x + 3*x^2))/(-1 + x + x^2)^3), where f(x) = 1/(1-x-x^2).
		

Crossrefs

Cf. A094440.

Programs

  • Mathematica
    t = Table[CoefficientList[((-1)^(n + 1)) Numerator[Factor[D[1/(1 - x - x^2), {x, n}]]/(n + 1)!], x], {n, 0, 10}]
    TableForm[t] (* array *)
    Flatten[t ]  (* sequence *)
  • PARI
    row(n) = if (n==0, [1], my(y=1/(1-x-x^2)); for (i=1, n, y = deriv(y)); (-1)^(n+1)*Vecrev(numerator(y/(n+1)!))); \\ Michel Marcus, Nov 27 2023

A368149 Triangular array T(n,k), read by rows: coefficients of strong divisibility sequence of polynomials p(1,x) = 1, p(2,x) = 1 + 2*x, p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where u = p(2,x), v = 1 - x^2.

Original entry on oeis.org

1, 1, 2, 2, 4, 3, 3, 10, 10, 4, 5, 20, 31, 20, 5, 8, 40, 78, 76, 35, 6, 13, 76, 184, 232, 161, 56, 7, 21, 142, 406, 636, 582, 308, 84, 8, 34, 260, 861, 1604, 1831, 1296, 546, 120, 9, 55, 470, 1766, 3820, 5215, 4630, 2640, 912, 165, 10, 89, 840, 3533, 8696
Offset: 1

Views

Author

Clark Kimberling, Dec 25 2023

Keywords

Comments

Because (p(n,x)) is a strong divisibility sequence, for each integer k, the sequence (p(n,k)) is a strong divisibility sequence of integers.

Examples

			First eight rows:
   1
   1    2
   2    4    3
   3   10   10    4
   5   20   31   20    5
   8   40   78   76   35    6
  13   76  184  232  161   56   7
  21  142  406  636  582  308  84  8
Row 4 represents the polynomial p(4,x) = 3 + 10*x + 10*x^2 + 4*x^3, so (T(4,k)) = (3,10,10,4), k=0..3.
		

Crossrefs

Cf. A000045 (column 1); A000027 (p(n,n-1)); A000244 (row sums), (p(n,1)); A033999 (alternating row sums), (p(n,-1)); A116415 (p(n,2)), A000748, (p(n,-2)); A152268, (p(n,3)); A190969, (p(n,-3)); A094440, A367208, A367209, A367210, A367211, A367297, A367298, A367299, A367300, A367301, A368150.

Programs

  • Mathematica
    p[1, x_] := 1; p[2, x_] := 1 + 2 x; u[x_] := p[2, x]; v[x_] := 1 - x^2;
    p[n_, x_] := Expand[u[x]*p[n - 1, x] + v[x]*p[n - 2, x]]
    Grid[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]
    Flatten[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]

Formula

p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where p(1,x) = 1, p(2,x) = 1 + 2*x, u = p(2,x), and v = 1 - x^2.
p(n,x) = k*(b^n - c^n), where k = -1/sqrt(5 + 4*x), b = (1/2)*(2*x + 1 - 1/k), c = (1/2)*(2*x + 1 + 1/k).

A368157 Triangular array T(n,k), read by rows: coefficients of strong divisibility sequence of polynomials p(1,x) = 1, p(2,x) = 1 + 2*x, p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where u = p(2,x), v = 1 + 2*x^2.

Original entry on oeis.org

1, 1, 2, 2, 4, 6, 3, 10, 16, 16, 5, 20, 46, 56, 44, 8, 40, 108, 184, 188, 120, 13, 76, 244, 496, 692, 608, 328, 21, 142, 520, 1248, 2088, 2480, 1920, 896, 34, 260, 1074, 2936, 5764, 8256, 8592, 5952, 2448, 55, 470, 2156, 6616, 14764, 24760, 31200, 28992
Offset: 1

Views

Author

Clark Kimberling, Jan 20 2024

Keywords

Comments

Because (p(n,x)) is a strong divisibility sequence, for each integer k, the sequence (p(n,k)) is a strong divisibility sequence of integers.

Examples

			First eight rows:
   1
   1    2
   2    4    6
   3   10   16    16
   5   20   46    56    44
   8   40  108   184   188   120
  13   76  244   496   692   608   328
  21  142  520  1248  2088  2480  1920  896
Row 4 represents the polynomial p(4,x) = 3 + 10*x + 16*x^2 + 16*x^3, so (T(4,k)) = (3,10,16,16), k=0..3.
		

Crossrefs

Cf. A000045 (column 1); A002605, (p(n,n-1)); A030195 (row sums), (p(n,1)); A182228 (alternating row sums), (p(n,-1)); A015545, (p(n,2)); A099012, (p(n,-2)); A087567, (p(n,3)); A094440, A367208, A367209, A367210, A367211, A367297, A367298, A367299, A367300, A367301, A368150, A368151, A368152, A368153, A368154, A368155, A368156.

Programs

  • Mathematica
    p[1, x_] := 1; p[2, x_] := 1 + 2 x; u[x_] := p[2, x]; v[x_] := 1 + 2x^2;
    p[n_, x_] := Expand[u[x]*p[n - 1, x] + v[x]*p[n - 2, x]]
    Grid[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]
    Flatten[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]

Formula

p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where p(1,x) = 1, p(2,x) = 1 + 2*x, u = p(2,x), and v = 1 + 2*x^2.
p(n,x) = k*(b^n - c^n), where k = -1/sqrt(5 + 4*x + 13*x^2), b = (1/2)*(2*x + 1 - 1/k), c = (1/2)*(2*x + 1 + 1/k).
Previous Showing 31-34 of 34 results.