Mirror Set, take-2 from sci.math
Hugo Pfoertner
all at abouthugo.de
Sat Mar 11 11:34:01 CET 2006
SeqFans,
found this morning in sci.math:
"Mirror Set, take-2" by Akira Bergman
http://groups.google.com/group/sci.math/msg/04826c1ffa6f6187
I don't know if he re-invents something well known, but at least he
found two sequences. The first one is well known:
Product of the first n factorials 1!*2!*3!*....*n!, which is
http://www.research.att.com/~njas/sequences/A000178
(two more terms might fit into the OEIS STU lines)
and the second is (product of first n factorials)/2^n
n A000178(n)
A000178(n)/2^n
1 1 1/2
2 2 1/2
3 12 3/2
4 288 18
5 34560 1080
6 24883200 388800
7 125411328000 979776000
8 5056584744960000 19752284160000
9 1834933472251084800000 3583854437990400000
10 6658606584104736522240000000 6502545492289781760000000
11 265790267296391946810949632000000000
129780403953316380278784000000000
12 127313963299399416749559771247411200000000000
31082510571142435729872991027200000000000
13 792786697595796795607377086400871488552960000000000000 96
775719921361913526291148242293882880000000000000
18,1080,388800,... is not in OEIS
Hugo Pfoertner
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