

A111868


The work performed by a function f:{1,...,n} > {1,...,n} is defined to be work(f) = Sum_{i=1..n} i  f(i); a(n) is equal to sum(work(f)) where the sum is over all functions f:{1,...,n}>{1,...,n}.


1



0, 4, 72, 1280, 25000, 544320, 13176688, 352321536, 10331213040, 330000000000, 11412466824440, 425000788033536, 16961005969166168, 722280443661271040, 32696077148437500000, 1567973246265311887360, 79415065141088329360992
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OFFSET

1,2


LINKS



FORMULA



EXAMPLE

When n=2 there are 4 maps {1,2}>{1,2}. these are (1 1), (2 2), (1 2), (2 1), where we show the map f:{1,2}>{1,2} as (f(1) f(2)). Adding up the work performed by these maps (from left to right as arranged above) gives a(2)=1+1+0+2=4.


MATHEMATICA



PROG



CROSSREFS



KEYWORD

easy,nonn,nice


AUTHOR



EXTENSIONS



STATUS

approved



