OFFSET
1,2
PROG
(GAP)
a := function(n)
local tom, mu, lens, orders, num, k;
tom := TableOfMarks(Concatenation("S", String(n)));
if tom = fail then tom := TableOfMarks(SymmetricGroup(n)); fi;
mu := MoebiusTom(tom).mu;
lens := LengthsTom(tom);
orders := OrdersTom(tom);
num := 0;
for k in [1 .. Length(lens)] do
if IsBound(mu[k]) then
num := num + mu[k] * lens[k] * orders[k]^3;
fi;
od;
return num;
end; # Stephen A. Silver, Feb 20 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 06 2003
EXTENSIONS
1 more term from David Wasserman, Mar 10 2005
a(6)-a(13) from Stephen A. Silver, Feb 20 2013
STATUS
approved