4th row of number array A083064.

Terms

a(0) =1a(1) =4a(2) =19a(3) =94a(4) =469a(5) =2344a(6) =11719a(7) =58594a(8) =292969a(9) =1464844a(10) =7324219a(11) =36621094a(12) =183105469a(13) =915527344a(14) =4577636719a(15) =22888183594a(16) =114440917969a(17) =572204589844