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A247982
Number of inequivalent expressions involving n operands, ignoring sign.
1
1, 5, 47, 733, 15907, 443825, 15129599, 609432421, 28322451979, 1491650309705, 87799033276583, 5711697248522077, 406948643125302163, 31515118552199419745, 2635823964117955940111, 236779241276954626064149, 22736883802469421935493211
OFFSET
1,2
COMMENTS
Similar to A140606, but for example, (a-b)/(c-d) and (b-a)/(c-d) are also regarded as the same.
LINKS
FORMULA
a(n) = A182173(n)/2. - Zhujun Zhang, Aug 11 2018
CROSSREFS
Sequence in context: A086555 A246040 A183773 * A222078 A061572 A140422
KEYWORD
nonn,more
AUTHOR
Azuma Seiichi, Sep 28 2014
EXTENSIONS
a(7)-a(17) from Muniru A Asiru, Aug 13 2018
STATUS
approved