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A203433
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Vandermonde determinant of the first n terms of (2,3,5,6,8,9,...) = (j+floor((j+1)/2)).
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4
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1, 1, 6, 72, 12960, 6531840, 84652646400, 3839844040704000, 6568897997313146880000, 46482573252667397426380800000, 16698920220108665726304214056960000000, 28359415513133792655802758561911537664000000000
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OFFSET
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1,3
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COMMENTS
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Each term divides its successor, as in A014402, and each term is divisible by the corresponding superfactorial, A000178(n), as in A203434.
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LINKS
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MATHEMATICA
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f[j_]:= j + Floor[(j+1)/2]; z = 20;
v[n_]:= Product[Product[f[k] - f[j], {j, k-1}], {k, 2, n}]
d[n_]:= Product[(i-1)!, {i, n}]
Table[v[n], {n, z}] (* this sequence *)
Table[v[n+1]/v[n], {n, z}] (* A014402 *)
Table[v[n]/d[n], {n, z}] (* A203434 *)
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PROG
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(Magma)
A203433:= func< n | n eq 1 select 1 else (&*[(&*[k-j+Floor(k/2)-Floor(j/2): j in [0..k-1]]) : k in [1..n-1]]) >;
(SageMath)
def A203433(n): return product(product(k-j+(k//2)-(j//2) for j in range(k)) for k in range(1, n))
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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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