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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A345694 For 1<=x<=n, 1<=y<=n with gcd(x,y)=1, write 1 = gcd(x,y) = u*x+v*y with u,v minimal; a(n) = m^2*s, where s is the population variance of the values of |u| and m is the number of such values.

Original entry on oeis.org

0, 2, 12, 28, 124, 168, 696, 1254, 2800, 3734, 9684, 13282, 27576, 34818, 51828, 71660, 129380, 153172, 254624, 312716, 413774, 496600, 767976, 879284, 1219286, 1422992, 1845842, 2173556, 3043292, 3345884, 4556174, 5288806, 6365966, 7188082, 8786288, 9615066
Offset: 1

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Author

Chai Wah Wu, Jun 24 2021

Keywords

Comments

The factor m^2 is to ensure that a(n) is an integer.
A345429(n) = m*mu where mu is the mean of the values of |u|.
The population standard deviation sqrt(s) appears to grow linearly with n.

Crossrefs

Programs

  • Python
    from statistics import pvariance
    from sympy.core.numbers import igcdex
    def A345694(n):
        zlist = [z for z in (igcdex(x,y) for x in range(1,n+1) for y in range(1,n+1)) if z[2] == 1]
        return pvariance(len(zlist)*abs(u) for u, v, w in zlist)
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