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A216705
a(n) = Product_{k=1..n} (81 - 9/k).
5
1, 72, 5508, 429624, 33832890, 2679564888, 213025408596, 16981168285224, 1356370816782267, 108509665342581360, 8691624193940766936, 696910230823250585232, 55927046023565859464868, 4491372003738673637024784, 360913821729000560118063000
OFFSET
0,2
COMMENTS
This sequence is generalizable: Product_{k=1..n} (q^2 - q/k) = (q^n/n!) * Product_{k=0..n-1} (q*k + q-1) = expansion of (1- x*q^2)^((1-q)/q).
LINKS
MAPLE
seq(product(81-9/k, k=1.. n), n=0..20);
seq((9^n/n!)*product(9*k+8, k=0.. n-1), n=0..20);
MATHEMATICA
Table[Product[81-9/k, {k, n}], {n, 0, 20}] (* Harvey P. Dale, Jul 20 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Sep 16 2012
STATUS
approved