Number of regions in a "cross" of width 3 and height n (see Comments for definition).

Terms

a(0) =64a(1) =104a(2) =176a(3) =304a(4) =492a(5) =778a(6) =1176a(7) =1732a(8) =2446a(9) =3416a(10) =4614a(11) =6172a(12) =8060a(13) =10340a(14) =13052a(15) =16388a(16) =20228a(17) =24852a(18) =30134a(19) =36206a(20) =43076a(21) =51092a(22) =60010a(23) =70186a(24) =81498a(25) =94180a(26) =108140a(27) =123938a(28) =141074a(29) =160308