

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
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

Similar to A140606, but for example, (ab)/(cd) and (ba)/(cd) are also regarded as the same.


LINKS

Muniru A Asiru, Table of n, a(n) for n = 1..100
Azuma Seiichi, Expressions with n variables


FORMULA

a(n) = A182173(n)/2.  Zhujun Zhang, Aug 11 2018


CROSSREFS

Cf. A140606, A182173.
Sequence in context: A086555 A246040 A183773 * A222078 A061572 A140422
Adjacent sequences: A247979 A247980 A247981 * A247983 A247984 A247985


KEYWORD

nonn,more


AUTHOR

Azuma Seiichi, Sep 28 2014


EXTENSIONS

a(7)a(17) from Muniru A Asiru, Aug 13 2018


STATUS

approved



