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 1-2 of 2 results.

A210197 Triangle of coefficients of polynomials u(n,x) jointly generated with A210198; see the Formula section.

Original entry on oeis.org

1, 3, 7, 1, 15, 5, 31, 17, 1, 63, 49, 7, 127, 129, 31, 1, 255, 321, 111, 9, 511, 769, 351, 49, 1, 1023, 1793, 1023, 209, 11, 2047, 4097, 2815, 769, 71, 1, 4095, 9217, 7423, 2561, 351, 13, 8191, 20481, 18943, 7937, 1471, 97, 1, 16383, 45057, 47103
Offset: 1

Views

Author

Clark Kimberling, Mar 18 2012

Keywords

Comments

Column 1: -1+2^n
Row sums: A048739
Alternating row sums: triangular numbers, A000217
For a discussion and guide to related arrays, see A208510.

Examples

			First five rows:
1
3
7....1
15...5
31...17...1
First three polynomials u(n,x): 1, 3, 7 + x.
		

Crossrefs

Essentially the same as the triangle in A257597.

Programs

  • Mathematica
    u[1, x_] := 1; v[1, x_] := 1; z = 16;
    u[n_, x_] := u[n - 1, x] + v[n - 1, x] + 1;
    v[n_, x_] := (x + 1)*u[n - 1, x] + v[n - 1, x] + 1;
    Table[Expand[u[n, x]], {n, 1, z/2}]
    Table[Expand[v[n, x]], {n, 1, z/2}]
    cu = Table[CoefficientList[u[n, x], x], {n, 1, z}];
    TableForm[cu]
    Flatten[%]   (* A210197 *)
    Table[Expand[v[n, x]], {n, 1, z}]
    cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
    TableForm[cv]
    Flatten[%]  (* A210198 *)
    Table[u[n, x] /. x -> 1, {n, 1, z}]  (* A048739 *)
    Table[v[n, x] /. x -> 1, {n, 1, z}]  (* A005409 *)
    Table[u[n, x] /. x -> -1, {n, 1, z}] (* A000217 *)
    Table[v[n, x] /. x -> -1, {n, 1, z}] (* A000027 *)

Formula

u(n,x)=u(n-1,x)+v(n-1,x)+1,
v(n,x)=(x+1)*u(n-1,x)+v(n-1,x)+1,
where u(1,x)=1, v(1,x)=1.

A257598 Triangle read by rows: coefficients of polynomials W_n(x), highest degree terms first.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 4, 1, 1, 1, 8, 1, 1, 1, 16, -4, 1, 1, 1, 1, 32, -16, 2, 1, 1, 1, 1, 64, -48, 8, 1, 1, 1, 1, 1, 128, -128, 32, 1, 1, 1, 1, 1, 256, -320, 112, -8, 1, 1, 1, 1, 1, 1, 512, -768, 352, -48, 2, 1, 1, 1, 1, 1, 1
Offset: 0

Views

Author

N. J. A. Sloane, Jun 06 2015

Keywords

Examples

			Triangle of coefficients begins:
1,
1, 1,
2, 1, 1,
4, 1, 1, 1,
8, 1, 1, 1,
16, -4, 1, 1, 1, 1,
32, -16, 2, 1, 1, 1, 1,
64, -48, 8, 1, 1, 1, 1, 1,
128, -128, 32, 1, 1, 1, 1, 1,
256, -320, 112 -8, 1, 1, 1, 1, 1, 1,
512, -768, 352 -48, 2, 1, 1, 1, 1, 1, 1,
...
The actual polynomials are:
0 1
1 x^2 + 1
2 2x^4 + x^2 + 1
3 4x^6 + x^4 + x^2 + 1
4 8x^8 + x^4 + x^2 + 1
5 16x^10 - 4x^8 + x^6 + x^4 + x^2 + 1
6 32x^12 - 16x^10 + 2x^8 + x^6 + x^4 + x^2 + 1
7 64x^14 - 48x^12 + 8x^10 + x^8 + x^6 + x^4 + x^2 + 1
8 128x^16 - 128x^14 + 32x^12 + x^8 + x^6 + x^4 + x^2 + 1
9 256x^18 - 320x^16 + 112x^14 - 8x^12 + x^10 + x^8 + x^6 + x^4 + x^2 + 1
10 512x^20 - 768x^18 + 352x^16 - 48x^14 + 2x^12 + x^10 + x^8 + x^6 + x^4 + x^2 + 1
...
		

Crossrefs

Cf. A257597.

Programs

  • PARI
    tabf(nn) = {pp = 1; p = x; for (n=1, nn, np = 2*x*p-pp-x^(n+1); w = p^2 - pp*np; forstep (j=poldegree(w), 0, -1, if (c = polcoeff(w, j), print1(c, ", "));); pp = p; p = np; print(););} \\ Michel Marcus, Aug 22 2015

Formula

W(n) = V(n+1)^2 - V(n)*V(n+2) where V(n) are the polynomials defined in A257597. - Michel Marcus, Aug 22 2015

Extensions

One typo in data corrected by Michel Marcus, Aug 22 2015
Showing 1-2 of 2 results.