For n >= 1, put A_n(z) = Sum_{j>=0} (n*j)!/(j!^n) * z^j and B_n(z) = Sum_{j>=0} (n*j)!/(j!^n) * z^j * (Sum_{k=1..j*n} (1/k)), and let b(n) be the largest integer for which exp(B_n(z)/(b(n)*A_n(z))) has integral coefficients. The sequence is b(n).

A131657

For n >= 1, put A_n(z) = Sum_{j>=0} (n*j)!/(j!^n) * z^j and B_n(z) = Sum_{j>=0} (n*j)!/(j!^n) * z^j * (Sum_{k=1..j*n} (1/k)), and let b(n) be the largest integer for which exp(B_n(z)/(b(n)*A_n(z))) has integral coefficients. The sequence is b(n).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =36a(6) =36a(7) =144a(8) =144a(9) =1440a(10) =1440a(11) =17280a(12) =17280a(13) =241920a(14) =3628800a(15) =29030400a(16) =29030400a(17) =1567641600a(18) =1567641600a(19) =783820800000

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