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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A195607 Numerator of floor(Phi*10^n)/10^n, where phi = (sqrt(5) + 1)/2 = A001622 is the Golden Ratio.

Original entry on oeis.org

1, 8, 161, 809, 809, 161803, 1618033, 16180339, 80901699, 404508497, 16180339887, 80901699437, 1618033988749, 8090169943749, 161803398874989, 809016994374947, 4045084971874737, 40450849718747371, 25281781074217107, 8090169943749474241
Offset: 0

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Author

M. F. Hasler, following a suggestion by Eric Angelini, Sep 21 2011

Keywords

Comments

Numerator of the decimal fraction of phi = 1.61803... truncated to a given number of decimal places.
The corresponding sequence for 1/phi = 0.61803... = phi-1 (also called the Golden Ratio) has a very similar behavior, because for both, the truncated decimal expansion can be simplified by the same factors 2^k*5^m.

Examples

			a(3) = 161 is the numerator of 1.61 = 161/100.
a(4) = 809 is the numerator of 1.618 = 1618/1000 = 809/500.

Crossrefs

Cf. A001622, A011551.
Cf. A195603 (analog for Pi), A195604 (for e), A195606 (for gamma).

Programs

  • Mathematica
    Floor[GoldenRatio #]/#&/@(10^Range[0,20])//Numerator (* Harvey P. Dale, Apr 14 2023 *)
  • PARI
    a(n,c=sqrt(5)/2+.5)=numerator(c\.1^n/10^n)  \\ M. F. Hasler, Sep 21 2011
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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