Length of n-th region in A376198.

Terms

a(0) =3a(1) =8a(2) =15a(3) =33a(4) =63a(5) =132a(6) =260a(7) =528a(8) =1057a(9) =2123a(10) =4236a(11) =8464a(12) =16932a(13) =33860a(14) =67732a(15) =135453a(16) =270927a(17) =541836a(18) =1083716a(19) =2167408a(20) =4334796a(21) =8669604a(22) =17339208a(23) =34678448a(24) =69356872a(25) =138713720a(26) =277427448a(27) =554854896a(28) =1109709804a(29) =2219419612