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A068181
a(n)=-1/b(2n) where 1/(e^y-e^(y/3))= sum(i=-1,inf,b(i)*y^i).
0
1, 18, 1944, 524880, 264539520, 214277011200, 254561089305600, 416971064282572800, 900657498850357248000, 2480410751833883860992000, 8483004771271882804592640000, 35272333838948488701496197120000
OFFSET
0,2
FORMULA
a(n)=A007661(6n+1)=A032031(3n+1)
CROSSREFS
Sequence in context: A072477 A249332 A019522 * A296614 A341842 A230818
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Mar 12 2002
STATUS
approved