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Array read by antidiagonals: T(m,n) is the number of (undirected) paths in the rook graph K_m X K_n.
2

%I #8 Feb 16 2025 08:34:04

%S 0,1,1,6,12,6,30,129,129,30,160,1984,4536,1984,160,975,45945,310542,

%T 310542,45945,975,6846,1524156,38298270,111933456,38298270,1524156,

%U 6846

%N Array read by antidiagonals: T(m,n) is the number of (undirected) paths in the rook graph K_m X K_n.

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GraphPath.html">Graph Path</a>.

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RookGraph.html">Rook Graph</a>.

%e Array begins:

%e ==============================================

%e m\n| 1 2 3 4 5 ...

%e ---+------------------------------------------

%e 1 | 0 1 6 30 160 ...

%e 2 | 1 12 129 1984 45945 ...

%e 3 | 6 129 4536 310542 38298270 ...

%e 4 | 30 1984 310542 111933456 ...

%e 5 | 160 45945 38298270 ...

%e ...

%Y Main diagonal is A288967.

%Y Rows 1..2 are A038155, A360878.

%Y Cf. A269562, A269565, A286418, A360851, A360855.

%K nonn,tabl,more

%O 1,4

%A _Andrew Howroyd_, Feb 25 2023