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.

A231731 Triangular array read by rows: row n shows the coefficients of the polynomial u(n) = c(0) + c(1)*x + ... + c(n)*x^(n) which is the numerator of the n-th convergent of the continued fraction [k, k, k, ... ], where k = 2*x + 1.

Original entry on oeis.org

1, 2, 2, 4, 4, 3, 10, 12, 8, 5, 20, 36, 32, 16, 8, 40, 88, 112, 80, 32, 13, 76, 204, 320, 320, 192, 64, 21, 142, 444, 840, 1040, 864, 448, 128, 34, 260, 932, 2048, 3040, 3136, 2240, 1024, 256, 55, 470, 1896, 4752, 8176, 10080, 8960, 5632, 2304, 512, 89, 840
Offset: 1

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Author

Clark Kimberling, Nov 13 2013

Keywords

Comments

Sum of numbers in row n: A006190(n). Left edge: A000045 (Fibonacci numbers). Right edge: powers of 2

Examples

			First 3 rows:
1 ... 2
2 ... 4 .... 4
3 ... 10 ... 12 ... 8
First 3 polynomials:  1 + 2*x, 2 + 4*x + 4*x^2, 3 + 10*x + 12*x^2 + 8*x^3.
		

Crossrefs

Programs

  • Mathematica
    t[n_] := t[n] = Table[2 x + 1, {k, 0, n}];
    b = Table[Factor[Convergents[t[n]]], {n, 0, 10}];
    p[x_, n_] := p[x, n] = Last[Expand[Numerator[b]]][[n]];
    u = Table[p[x, n], {n, 1, 10}]
    v = CoefficientList[u, x]; Flatten[v]