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%I #9 Feb 17 2026 20:33:58
%S 3,4,4,8,24,8,16,56,56,16,32,160,378,160,32,64,352,2644,2644,352,64,
%T 128,896,18478,23736,18478,896,128,256,1920,130992,376440,376440,
%U 130992,1920,256,512,4608,931274,3364312,10582480,3364312,931274,4608,512,1024,9728,6629564,48690960,255107524,255107524,48690960,6629564,9728,1024
%N Array read by antidiagonals: T(n,k) is the number of Hamiltonian cycles in the n X k truncated square lattice graph.
%H Andrew Howroyd, <a href="/A392422/b392422.txt">Table of n, a(n) for n = 1..120</a> (first 15 antidiagonals)
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianCycle.html">Hamiltonian Cycle</a>.
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TruncatedSquareLatticeGraph.html">Truncated Square Lattice Graph</a>.
%F T(n,k) = T(k,n).
%F T(n,1) = 2^n for n > 1.
%e Array begins:
%e ====================================================
%e n\k | 1 2 3 4 5 6 ...
%e ----+-----------------------------------------------
%e 1 | 3 4 8 16 32 64 ...
%e 2 | 4 24 56 160 352 896 ...
%e 3 | 8 56 378 2644 18478 130992 ...
%e 4 | 16 160 2644 23736 376440 3364312 ...
%e 5 | 32 352 18478 376440 10582480 255107524 ...
%e 6 | 64 896 130992 3364312 255107524 7596623856 ...
%e ...
%Y Main diagonal is A393482.
%Y Cf. A270273.
%K nonn,tabl
%O 1,1
%A _Andrew Howroyd_, Feb 17 2026