OFFSET
1,2
COMMENTS
Index numbers (compare A055089) of transpositions.
LINKS
Tilman Piesk, Table of n, a(n) for n = 1..2016
Tilman Piesk, Arrays of permutations (Wikiversity)
FORMULA
EXAMPLE
T(3,2) = 3*4! + Sum( 2 <= i <= 3 ) i!
= 3*4! + 2! + 3!
= 3*24 + 2 + 6 = 80.
The array starts:
1, 2, 6, 24, 120,...
5, 14, 54, 264, 1560,...
21, 80, 390, 2304, 15960,...
105, 512, 3030, 21024,167160,...
633, 3752, 26070,207504,1860600,...
MAPLE
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Tilman Piesk, Jul 07 2012
STATUS
approved