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.

A065179 Number of site swap patterns with 3 balls and exact period n.

Original entry on oeis.org

1, 3, 12, 42, 156, 554, 2028, 7350, 26936, 98874, 365196, 1353520, 5039580, 18831306, 70626140, 265741350, 1002984060, 3796211692, 14406086604, 54801192684, 208932673508, 798218225802, 3055417434732, 11716355452900
Offset: 1

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Author

Antti Karttunen, Oct 19 2001

Keywords

Examples

			We have one period 1 (3, the three-ball cascade), three period two (42/24, 51/15 = three-ball shower and 60/06) and twelve period three 3-ball siteswaps (423, 441, 450, 522, 531, 603, 612, 630, 711, 720, 801, 900) (The average of digits is always 3).
		

Crossrefs

Row 3 of A065177.

Programs

  • Maple
    [seq(DistSS(p,3),p=1..60)];
    A065179 := proc(n)
        add( mobius(n/d)*(4^d-3^d),d=numtheory[divisors](n)) /n ;
    end proc:
    seq(A065179(n),n=1..30) ; # R. J. Mathar, Aug 05 2015
  • Mathematica
    a[n_] := DivisorSum[n, MoebiusMu[n/#]*(4^# - 3^#)&]/n; Array[a, 25] (* Jean-François Alcover, Mar 06 2016 *)

Formula

G.f.: Sum_{k>=1} mu(k) * log(1 + x^k/(1 - 4*x^k))/k. - Seiichi Manyama, Apr 14 2025