a(n) is the value of row n in triangle A083093 seen as ternary number.

Terms

a(0) =1a(1) =4a(2) =16a(3) =28a(4) =112a(5) =448a(6) =784a(7) =3136a(8) =12301a(9) =19684a(10) =78736a(11) =314944a(12) =551152a(13) =2204608a(14) =8818432a(15) =15432256a(16) =61729024a(17) =242132884a(18) =387459856a(19) =1549839424a(20) =6199180549a(21) =10848875968a(22) =43395503872a(23) =173577055372a(24) =303766932781