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Terms

a(0) =1a(1) =3a(2) =8a(3) =21a(4) =55a(5) =149a(6) =404a(7) =1097a(8) =2981a(9) =8104a(10) =22027a(11) =59875a(12) =162755a(13) =442414a(14) =1202605a(15) =3269018a(16) =8886111a(17) =24154953a(18) =65659970a(19) =178482301a(20) =485165196a(21) =1318815735a(22) =3584912847a(23) =9744803447a(24) =26489122130a(25) =72004899338a(26) =195729609429a(27) =532048240602