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%I #17 Apr 13 2017 12:26:03
%S 1,3,23,404,9524,357264,16987536,1061800704,87631559424,8894837836800,
%T 1063107188812800,151494084266803200,25373057708287180800,
%U 5011895098867920076800,1135276451701834014720000,292340783888393707192320000,84048723407048386326036480000
%N a(n) = (n!)^2 * Sum_{k=1..n} A008836(k)/k^2.
%H Daniel Suteu, <a href="/A280654/b280654.txt">Table of n, a(n) for n = 1..100</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Liouville_function">Liouville function</a>.
%F Limit_{n->infinity} a(n)/(n!)^2 = zeta(4)/zeta(2) = Pi^2/15.
%t Table[(n!)^2 * Sum[(-1)^PrimeOmega[k]/k^2, {k, n}], {n, 20}] (* _Indranil Ghosh_, Apr 13 2017 *)
%o (PARI) a(n) = (n!)^2 * sum(k=1,n,(-1)^bigomega(k)/k^2);
%Y Cf. A001044, A008836, A182448 (Pi^2/15).
%K nonn
%O 1,2
%A _Daniel Suteu_, Apr 12 2017