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.

A327315 Irregular triangular array read by rows: row n shows the coefficients of this polynomial of degree n: (1/n!)*(numerator of n-th derivative of (x-2)/(x^2-x+1)).

Original entry on oeis.org

-2, 1, -1, 4, -1, 1, 3, -6, 1, 2, -4, -6, 8, -1, 1, -10, 10, 10, -10, 1, -1, -6, 30, -20, -15, 12, -1, -2, 7, 21, -70, 35, 21, -14, 1, -1, 16, -28, -56, 140, -56, -28, 16, -1, 1, 9, -72, 84, 126, -252, 84, 36, -18, 1, 2, -10, -45, 240, -210, -252, 420, -120
Offset: 0

Views

Author

Clark Kimberling, Nov 01 2019

Keywords

Comments

Conjecture: The numbers n for which the n-th polynomial is irreducible are given by A069353.

Examples

			First eight rows:
  -2,   1;
  -1,   4,  -1;
   1,   3,  -6,   1;
   2,  -4,  -6,   8,  -1;
   1, -10,  10,  10, -10,   1;
  -1,  -6,  30, -20, -15,  12,  -1;
  -2,   7,  21, -70,  35,  21, -14,  1;
  -1,  16, -28, -56, 140, -56, -28, 16, -1;
First eight polynomials:
  -2 + x
  -1 + 4 x - x^2
   1 + 3 x - 6 x^2 + x^3
   2 - 4 x - 6 x^2 + 8 x^3 - x^4
   (1 + x) (1 - 11 x + 21 x^2 - 11 x^3 + x^4)
  -1 - 6 x + 30 x^2 - 20 x^3 - 15 x^4 + 12 x^5 - x^6
   (-2 + x) (1 - 3 x - 12 x^2 + 29 x^3 - 3 x^4 - 12 x^5 + x^6)
  -1 + 16 x - 28 x^2 - 56 x^3 + 140 x^4 - 56 x^5 - 28 x^6 + 16 x^7 - x^8
		

Crossrefs

Programs

  • Mathematica
    g[x_, n_] := Numerator[ Factor[D[(x - 2)/(x^2 - x + 1), {x, n}]]]
    Column[Expand[Table[g[x, n]/n!, {n, 0, 12}]]] (* A327315 polynomials *)
    h[n_] := CoefficientList[g[x, n]/n!, x];
    Table[h[n], {n, 0, 10}]  (* A327315 sequence *)
    Column[%]   (* A327315 array *)

A328647 Irregular triangular array read by rows: row n shows the coefficients of this polynomial of degree n: (1/n!)*(numerator of n-th derivative of (1+x)/(x^2-3x+1)).

Original entry on oeis.org

1, 1, 4, -2, -1, 11, -12, 3, 1, 29, -44, 24, -4, -1, 76, -145, 110, -40, 5, 1, 199, -456, 435, -220, 60, -6, -1, 521, -1393, 1596, -1015, 385, -84, 7, 1, 1364, -4168, 5572, -4256, 2030, -616, 112, -8, -1, 3571, -12276, 18756, -16716, 9576, -3654, 924, -144
Offset: 0

Views

Author

Clark Kimberling, Nov 01 2019

Keywords

Comments

The first 201 polynomials are irreducible. Column 1 of the array: A002879 (odd-indexed Lucas numbers). Row sums: A000032 (Lucas numbers). Alternating row sums: essentially 5*A030191.

Examples

			First eight rows:
     1,     1;
     4,    -2,   -1;
    11,   -12,    3,     1;
    29,   -44,   24,    -4,   -1;
    76,  -145,  110,   -40,    5,    1;
   199,  -456,  435,  -220,   60,   -6,  -1;
   521, -1393, 1596, -1015,  385,  -84,   7,  1;
  1364, -4168, 5572, -4256, 2030, -616, 112, -8, -1;
First eight polynomials:
1 + x
4 - 2 x - x^2
11 - 12 x + 3 x^2 + x^3
29 - 44 x + 24 x^2 - 4 x^3 - x^4
76 - 145 x + 110 x^2 - 40 x^3 + 5 x^4 + x^5
199 - 456 x + 435 x^2 - 220 x^3 + 60 x^4 - 6 x^5 - x^6
521 - 1393 x + 1596 x^2 - 1015 x^3 + 385 x^4 - 84 x^5 + 7 x^6 + x^7
1364 - 4168 x + 5572 x^2 - 4256 x^3 + 2030 x^4 - 616 x^5 + 112 x^6 - 8 x^7 - x^8
		

Crossrefs

Programs

  • Mathematica
    g[x_, n_] := Numerator[ Factor[D[(1 + x)/(x^2 - 3 x + 1), {x, n}]]]
    Column[Expand[Table[g[x, n]/n!, {n, 0, 12}]]] (* polynomials *)
    h[n_] := CoefficientList[g[x, n]/n!, x]
    Table[h[n], {n, 0, 10}]
    Column[%]  (* A328647 array *)

A328649 Irregular triangular array read by rows: row n shows the coefficients of the following polynomial of degree n: (1/n!)*(numerator of n-th derivative of (x-2)/(1-x-x^2)).

Original entry on oeis.org

2, -1, -1, -4, 1, 3, 3, 6, -1, -4, -12, -6, -8, 1, 7, 20, 30, 10, 10, -1, -11, -42, -60, -60, -15, -12, 1, 18, 77, 147, 140, 105, 21, 14, -1, -29, -144, -308, -392, -280, -168, -28, -16, 1, 47, 261, 648, 924, 882, 504, 252, 36, 18, -1, -76, -470, -1305
Offset: 0

Views

Author

Clark Kimberling, Nov 01 2019

Keywords

Comments

The first 201 polynomials are irreducible. Column 1: signed Lucas numbers (A000032).

Examples

			First eight rows:
    2,   -1;
   -1,   -4,    1;
    3,    3,    6,   -1;
   -4,  -12,   -6,   -8,    1;
    7,   20,   30,   10,   10,   -1;
  -11,  -42,  -60,  -60,  -15,  -12,   1;
   18,   77,  147,  140,  105,   21,  14,  -1;
  -29, -144, -308, -392, -280, -168, -28, -16, 1;
First eight polynomials:
   2 - x
  -1 - 4 x + x^2
   3 + 3 x + 6 x^2 - x^3
  -4 - 12 x - 6 x^2 - 8 x^3 + x^4
   7 + 20 x + 30 x^2 + 10 x^3 + 10 x^4 - x^5
  -11 - 42 x - 60 x^2 - 60 x^3 - 15 x^4 - 12 x^5 + x^6
   18 + 77 x + 147 x^2 + 140 x^3 + 105 x^4 + 21 x^5 + 14 x^6 - x^7
  -29 - 144 x - 308 x^2 - 392 x^3 - 280 x^4 - 168 x^5 - 28 x^6 - 16 x^7 + x^8
		

Crossrefs

Programs

  • Mathematica
    g[x_, n_] := Numerator[ Factor[D[(x - 2)/(1 - x - x^2), {x, n}]]]
    Column[Expand[Table[g[x, n]/n!, {n, 0, 12}]]]  (* A328649 polynomials *)
    h[n_] := CoefficientList[g[x, n]/n!, x];
    Table[h[n], {n, 0, 10}] (* A328649 sequence *)
    Column[%] (* A328649 array *)

A328650 Triangular array read by rows: row n shows the coefficients of this polynomial of degree n: (1/n!)*(numerator of n-th derivative of 1)/(1-x-2x^2).

Original entry on oeis.org

-1, 1, 4, -3, -6, -12, 5, 24, 24, 32, -11, -50, -120, -80, -80, 21, 132, 300, 480, 240, 192, -43, -294, -924, -1400, -1680, -672, -448, 85, 688, 2352, 4928, 5600, 5376, 1792, 1024, -171, -1530, -6192, -14112, -22176, -20160, -16128, -4608, -2304, 341, 3420
Offset: 0

Views

Author

Clark Kimberling, Nov 01 2019

Keywords

Comments

It appears that the number of nonconstant polynomial divisors of the n-th polynomial is given by A032741.

Examples

			First eight rows:
    -1;
     1,    4;
     3,   -6,  -12;
     5,   24,   24,    32;
   -11,  -50, -120,   -80,   -80;
    21,  132,  300,   480,   240,  192;
   -43, -294, -924, -1400, -1680, -672, -448;
    85,  688, 2352,  4928,  5600, 5376, 1792, 1024;
First eight polynomials:
-1
1 + 4 x
-3 (1 + 2 x + 4 x^2)
(1 + 4 x) (5 + 4 x + 8 x^2)
-11 - 50 x - 120 x^2 - 80 x^3 - 80 x^4
3 (1 + 4 x) (1 + 2 x + 4 x^2) (7 + 2 x + 4 x^2)
-43 - 294 x - 924 x^2 - 1400 x^3 - 1680 x^4 - 672 x^5 - 448 x^6
(1 + 4 x) (5 + 4 x + 8 x^2) (17 + 56 x + 120 x^2 + 32 x^3 + 32 x^4)
		

Crossrefs

Programs

  • Mathematica
    g[x_, n_] := Numerator[ Factor[D[1/(1 - x - 2 x^2), {x, n}]]]
    Column[Expand[Table[g[x, n]/n!, {n, 0, 12}]]]  (* A328650 polynomials *)
    h[n_] := CoefficientList[g[x, n]/n!, x];
    Table[h[n], {n, 0, 10}] (* A328650 sequence *)
    Column[%] (* A328650 array *)
Showing 1-4 of 4 results.