Total number of single toothpicks after n-th stage in the Y-toothpick structure of A160120.

Terms

a(0) =0a(1) =3a(2) =12a(3) =21a(4) =48a(5) =57a(6) =84a(7) =111a(8) =174a(9) =201a(10) =228a(11) =255a(12) =318a(13) =363a(14) =426a(15) =507a(16) =660a(17) =741a(18) =768a(19) =795a(20) =858a(21) =903a(22) =966a(23) =1047a(24) =1200a(25) =1299a(26) =1362a(27) =1443a(28) =1596a(29) =1749