A086984 Number of arrangements of n labeled balls in n labeled columns where only 1 column may have more than 1 ball.
1, 6, 60, 696, 9120, 134640, 2227680, 41005440, 833172480, 18546796800, 449223667200, 11766674304000, 331501679308800, 9997170543360000, 321355745238528000, 10969253822951424000, 396269940892041216000
Offset: 1
Keywords
Examples
a(2)=6; .. .. -G -R R- G- RG GR -R -G G- R-
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..402
Programs
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Mathematica
Table[n!+Sum[Binomial[n-1,n-k],{k,2,n}]n n!,{n,20}] (* Harvey P. Dale, Nov 29 2019 *) -
PARI
a(n)=n!+sum(i=2,n,binomial(n-1,n-i)*n*n!)
Formula
a(n) = n! + Sum_{i=2..n} binomial(n-1, n-i)*n*n!.
Comments