Partial sums of round(3^n/10).

Terms

a(0) =0a(1) =0a(2) =1a(3) =4a(4) =12a(5) =36a(6) =109a(7) =328a(8) =984a(9) =2952a(10) =8857a(11) =26572a(12) =79716a(13) =239148a(14) =717445a(15) =2152336a(16) =6457008a(17) =19371024a(18) =58113073a(19) =174339220a(20) =523017660a(21) =1569052980a(22) =4707158941a(23) =14121476824a(24) =42364430472a(25) =127093291416