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A260784
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Coefficients in a certain low-temperature series expansion.
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1
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0, 24, 1440, 181440, 43545600, 17882726400, 11333177856000, 10257397742592000, 12540115964952576000, 19887027595237490688000, 39679473692005106319360000, 97249082487667949725286400000, 287164491478121796028858368000000, 1005464789964467723115455053824000000
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OFFSET
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1,2
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LINKS
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MAPLE
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local a, d1, d2, d3, d4, d33half ;
a := 0 ;
for d2 from 0 do
if 2*d2 > n then
break;
end if;
for d3 from 0 do
if 2*d2 +3*d3 > n then
break;
end if;
for d4 from 0 do
if 2*d2 +3*d3+4*d4 > n then
break;
end if;
d1 := n-2*d2-3*d3-4*d4 ;
if d1 >= 0 and type(d1+d3, 'even') then
d13half := (d1+d3)/2 ;
a := a+(d1+d2+d3+d4)!/d1!/d2!/d3!/d4!*(-1)^(d2+d3+d4-1)*2^d2
/(d1+d2+d3+d4)*binomial(d1+d3, d13half)^2 ;
end if;
end do:
end do:
end do:
a*n!/2 ;
end proc:
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MATHEMATICA
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"Listing 1" in Siudem et al. (2014) gives Mathematica code for the fractions a(n)/(2n)!.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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