p-INVERT of the positive integers, where p(S) = 1 - 3*S^2.

Terms

a(0) =0a(1) =3a(2) =12a(3) =39a(4) =132a(5) =456a(6) =1572a(7) =5409a(8) =18612a(9) =64053a(10) =220440a(11) =758640a(12) =2610840a(13) =8985147a(14) =30922188a(15) =106418031a(16) =366235308a(17) =1260390744a(18) =4337606988a(19) =14927778921a(20) =51373622388a(21) =176801189997a(22) =608457401520