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.

A193078 Decimal expansion of the coefficient of x in the reduction of phi^(-x) by x^2->x+1, where phi=(1+sqrt(5))/2 is the golden ratio (A001622) (negated).

Original entry on oeis.org

3, 9, 6, 8, 2, 1, 7, 6, 2, 2, 5, 4, 6, 3, 9, 9, 6, 6, 8, 6, 8, 3, 1, 5, 6, 0, 2, 9, 7, 3, 5, 3, 0, 1, 9, 7, 1, 6, 7, 6, 0, 2, 7, 5, 4, 8, 5, 1, 5, 4, 4, 8, 5, 3, 3, 0, 5, 9, 9, 0, 1, 0, 9, 9, 9, 9, 6, 1, 9, 7, 5, 4, 0, 3, 0, 0, 6, 9, 5, 4, 9, 7, 6, 3, 0, 7, 2, 8, 7, 1, 9, 2, 0, 9, 6, 8, 0, 7, 7, 7
Offset: 0

Views

Author

Clark Kimberling, Jul 15 2011

Keywords

Comments

Reduction of a function f(x) by a substitution q(x)->s(x) is introduced at A193010.

Examples

			-0.39682176225463996686831560297353019716760...
		

Crossrefs

Programs

  • Mathematica
    t = GoldenRatio
    f[x_] := t^(-x); r[n_] := Fibonacci[n];
    c[n_] := SeriesCoefficient[Series[f[x], {x, 0, n}], n]
    u1 = N[Sum[c[n]*r[n], {n, 0, 100}], 100]
    RealDigits[u1, 10]

Formula

From Amiram Eldar, Jan 19 2022: (Start)
Equals Sum_{k>=0} (-log(phi))^k*Fibonacci(k)/k!.
Equals -(phi^sqrt(5) - 1)/(sqrt(5)*phi^phi). (End)