Smallest member of bi-unitary sociable quadruples.

Terms

a(0) =162a(1) =1026a(2) =1620a(3) =10098a(4) =10260a(5) =41800a(6) =51282a(7) =100980a(8) =107920a(9) =512820a(10) =1479006a(11) =4612720a(12) =4938136a(13) =14790060a(14) =14800240a(15) =23168840a(16) =28158165a(17) =32440716a(18) =55204500a(19) =81128632a(20) =84392560a(21) =88886448a(22) =209524210a(23) =283604220a(24) =325903500a(25) =498215416a(26) =572062304a(27) =881697520