

A110348


a(2) = 1 by definition; otherwise a(n) = A109347(n)/n.


1



1, 1, 8, 45, 504, 5040, 86400, 1247400, 28828800, 544864320, 15850598400, 370507737600, 12996271411200, 362038989312000, 14867734494412800, 480878287553664000, 22629566473113600000, 833522365093017600000
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OFFSET

1,3


LINKS



FORMULA

a(2n+1) = (n+1)(n+2)...(2n1)(2n)(2n+2) ...(3n+1)(3n+2). a(2n) = (1/2)(n+1)(n+2)...(2n2)(2n1)(2n+1)(2n+2)...(3n1)(3n).


EXAMPLE

a(3) = 2*3*4/3 = 8, a(6)= 3*4*5*7*8*9/6 = 5040.


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



