Use R to list all possible sums from rolling three dice.

outer(1:6, 1:6, "+") + c(1:6)
##      [,1] [,2] [,3] [,4] [,5] [,6]
## [1,]    3    4    5    6    7    8
## [2,]    5    6    7    8    9   10
## [3,]    7    8    9   10   11   12
## [4,]    9   10   11   12   13   14
## [5,]   11   12   13   14   15   16
## [6,]   13   14   15   16   17   18

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