|
|
A266913
|
|
Denominator of the volume of d dimensional symmetric convex cuboid with constraints |x1 + x2 + ... xd| <= 1 and |x1|, |x2|, ..., |xd| <= 1.
|
|
1
|
|
|
1, 1, 3, 12, 5, 180, 315, 2240, 567, 907200, 51975, 13305600, 289575, 80720640, 212837625, 3487131648000, 2297295, 64023737057280, 14849255421, 28963119144960000, 17717861581875, 140500090972200960000, 16436269594119375, 6204484017332394393600, 40639128117328125
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
COMMENTS
|
Reference A. Dubickas shows that all the volume integrals are rational with V[d] <= 2^d.
|
|
LINKS
|
|
|
EXAMPLE
|
For d = 3 the volume is 16/3, for each volume we have V[1] = 2, V[2] = 3, V[3] = 16/3, V[4] = 115/12, V[5] = 88/5, V[6] = 5887/180, V[7] = 19328/315, V[8] = 259723/2240, V[9] = 124952/567, V[10] = 381773117/907200, etc.
|
|
MATHEMATICA
|
V[d_] := Integrate[Boole[Abs[Sum[x[i], {i, 1, d}]] <= 1],
Table[x[i], {i, 1, d}] \[Element]
v[d_] := With[{a = Array[x, d]}, RegionMeasure @ ImplicitRegion[a ∈ Cuboid[-Table[1, d], Table[1, d]] && -1 <= Total[a] <= 1, a]] (* Carl Woll *)
v[d_] := 2^(d+1)/(Pi) Integrate[Sin[t]^(d+1)/t^(n+1), {t, 0, Infinity}] (* Carl Woll *)
|
|
CROSSREFS
|
The numerator sequence is given by A269067.
Cf. A199832 The rational coefficient of the leading coefficient of the empirical rows duplicates these volume integrals in sequence. This is not a proof.
|
|
KEYWORD
|
nonn,frac
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|