Second differences of A045623, prefixed by an initial 1.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =20a(5) =44a(6) =96a(7) =208a(8) =448a(9) =960a(10) =2048a(11) =4352a(12) =9216a(13) =19456a(14) =40960a(15) =86016a(16) =180224a(17) =376832a(18) =786432a(19) =1638400a(20) =3407872a(21) =7077888a(22) =14680064a(23) =30408704a(24) =62914560a(25) =130023424a(26) =268435456a(27) =553648128a(28) =1140850688a(29) =2348810240