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A103999
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Square array T(M,N) read by antidiagonals: number of dimer tilings of a 2M x 2N Klein bottle.
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8
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1, 1, 1, 1, 6, 1, 1, 16, 34, 1, 1, 54, 196, 198, 1, 1, 196, 1666, 2704, 1154, 1, 1, 726, 16384, 64152, 37636, 6726, 1, 1, 2704, 171394, 1844164, 2549186, 524176, 39202, 1, 1, 10086, 1844164, 57523158, 220581904, 101757654, 7300804, 228486, 1
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OFFSET
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0,5
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LINKS
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FORMULA
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T(M, N) = Product_{m=1..M} Product_{n=1..N} ( 4sin(Pi*(4n-1)/(4N))^2 + 4sin(Pi*(2m-1)/(2M))^2 ).
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EXAMPLE
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Array begins:
1, 1, 1, 1, 1, 1, 1, ...
1, 6, 34, 198, 1154, 6726, 39202, ...
1, 16, 196, 2704, 37636, 524176, 7300804, ...
1, 54, 1666, 64152, 2549186, 101757654, 4064620168, ...
1, 196, 16384, 1844164, 220581904, 26743369156, 3252222705664, ...
1, 726,171394, 57523158, 21050622914, 7902001927776, 2988827208115522, ...
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MATHEMATICA
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T[m_, n_] := Product[4 Sin[(4k-1) Pi/(4n)]^2 + 4 Cos[j Pi/(2m+1)]^2, {j, 1, m}, {k, 1, n}] // Round;
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PROG
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(PARI) default(realprecision, 120);
{T(n, k) = round(prod(a=1, n, prod(b=1, k, 4*sin((4*a-1)*Pi/(4*n))^2+4*sin((2*b-1)*Pi/(2*k))^2)))} \\ Seiichi Manyama, Jan 11 2021
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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