Squares of double factorials: (1*3*5*...*(2n-1))^2 = ((2*n-1)!!)^2.

A001818

Squares of double factorials: (1*3*5*...*(2n-1))^2 = ((2*n-1)!!)^2.

Terms

    a(0) =1a(1) =1a(2) =9a(3) =225a(4) =11025a(5) =893025a(6) =108056025a(7) =18261468225

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