a(n) = A023900(n*A000396(n)).A379725a(n) = A023900(n*A000396(n)).Terms a(0) =2a(1) =6a(2) =-60a(3) =126a(4) =-32760a(5) =-262140a(6) =-3145716a(7) =2147483646External referencesoeis: A379725