p-INVERT of the Fibonacci sequence (A000045), where p(S) = (1 - S)^3.

Terms

a(0) =3a(1) =9a(2) =28a(3) =84a(4) =246a(5) =707a(6) =2001a(7) =5592a(8) =15461a(9) =42357a(10) =115122a(11) =310716a(12) =833472a(13) =2223471a(14) =5902415a(15) =15598896a(16) =41058423a(17) =107673601a(18) =281416248a(19) =733229412a(20) =1904957434a(21) =4936026747a(22) =12758472189a(23) =32901998472a(24) =84667043769a(25) =217437602349a(26) =557361593902