Product_{n>=1} 1 / (1 - x^n)^(a(n)/n!) = 1 + arctanh(x).

A354118

Product_{n>=1} 1 / (1 - x^n)^(a(n)/n!) = 1 + arctanh(x).

Terms

    a(0) =1a(1) =-2a(2) =2a(3) =-8a(4) =64a(5) =-544a(6) =3968a(7) =-29952a(8) =378880a(9) =-5938176a(10) =68247552a(11) =-793491456a(12) =15949529088a(13) =-306908848128

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