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A168431
General number of transpositions of n objects with repetitions.
0
1, 2, 9, 46, 245, 1601
OFFSET
1,2
FORMULA
Apparently a(n)=A005651(n)-1, n>1. [From R. J. Mathar, Nov 26 2009]
EXAMPLE
a(1)=1!/1!=1 because A035294(1)=1; a(2)=2!/(1!*1!)=2 because A035294(2)=1; a(3)=3!/(1!*1!*1!)+3!/(2!*1!)=9 because A035294(3)=2; a(4)=4!/(1!*1!*1!*1!)+4!/(2!*1!*1!)+4!/(2!*2!)+4!/(3!*1!)=46 because A035294(4)=4; a(5)=5!/(1!*1!*1!*1!*1!)+5!/(2!*1!*1!*1!)+5!/(2!*2!*1!)+5!/(3!*1!*1!)+5!/(3!*2!)+5!/(4!*1!)=245 because A035294(5)=6; a(6)=6!/(1!*1!*1!*1!*1!*1!)+6!/(2!*1!*1!*1!*1!)+6!/(2!*2!*1!*1!)+6!/(2!*2!*2!)+6!/(3!*1!*1!*1!)+6!/(3!*2!*1!)+6!/(3!*3!)+6!/(4!*1!*1!)+6!/(4!*2!)+6!/(5!*1!)=1601 because A035294(6)=10.
CROSSREFS
Cf. A035294.
Cf. A036038. [From R. J. Mathar, Nov 26 2009]
Sequence in context: A251178 A162725 A268171 * A036726 A219197 A340942
KEYWORD
nonn
AUTHOR
STATUS
approved