3-fold convolution of A000302 (powers of 4).

Terms

a(0) =1a(1) =12a(2) =96a(3) =640a(4) =3840a(5) =21504a(6) =114688a(7) =589824a(8) =2949120a(9) =14417920a(10) =69206016a(11) =327155712a(12) =1526726656a(13) =7046430720a(14) =32212254720a(15) =146028888064a(16) =657129996288