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A328746
Number of loops of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).
0
0, 1, 1, 1, 2, 5, 72, 12151, 53146457
OFFSET
0,5
FORMULA
a(n) = (A057771(n)+A057996(n))/2.
CROSSREFS
For the number of group-like algebraic structures of order n, see:
Semigroups: A027851 or A001423 (commutative: A001426);
Monoids: A058129 or A058133 (commutative: A058131);
Quasigroups: A057991 or A058171 (commutative: A057992);
Loops: A057771 or this sequence (commutative: A089925);
Groups: A000001 (commutative: A000688);
Rings: A027623 or A038036 (commutative: A037289);
Rings with unity: A037291;
Fields: A069513.
Sequence in context: A309366 A007506 A042693 * A172037 A301993 A128297
KEYWORD
nonn,hard,more
AUTHOR
Jianing Song, Oct 26 2019
STATUS
approved