Consider the following set of dice with nonstandard pips:
Die $A$: $1$ $4$ $4$ $4$ $4$ $4$
Die $B$: $2$ $2$ $2$ $5$ $5$ $5$
Die $C$: $3$ $3$ $3$ $3$ $3$ $6$
A game is played by two players picking a die in turn and rolling it. The player who rolls the highest value wins.
If the first player picks die $A$ and the second player picks die $B$ we get
$P(\text{second player wins}) = 7/12 \gt 1/2$.
If the first player picks die $B$ and the second player picks die $C$ we get
$P(\text{second player wins}) = 7/12 \gt 1/2$.
If the first player picks die $C$ and the second player picks die $A$ we get
$P(\text{second player wins}) = 25/36 \gt 1/2$.
So whatever die the first player picks, the second player can pick another die and have a larger than $50\%$ chance of winning.
A set of dice having this property is called a nontransitive set of dice.
We wish to investigate how many sets of nontransitive dice exist. We will assume the following conditions:
For $N = 7$ we find there are $9780$ such sets.
How many are there for $N = 30$?