OFFSET
0,5
LINKS
Wikipedia, Permutation
EXAMPLE
a(3) = 1: (13)(2).
a(4) = 2: (124)(3), (142)(3).
a(5) = 12: (1235)(4), (1253)(4), (1325)(4), (1352)(4), (1523)(4), (1532)(4), (124)(35), (142)(35), (125)(34), (152)(34), (13)(245), (13)(254).
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 17 2023
STATUS
approved