a(n) = |b(n)| where b(n) = -b(n-1) + 6*b(n-3) with b(0)=0, b(1)=1, b(2)=1.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =7a(5) =1a(6) =5a(7) =47a(8) =53a(9) =23a(10) =259a(11) =577a(12) =715a(13) =839a(14) =4301a(15) =8591a(16) =3557a(17) =22249a(18) =73795a(19) =95137a(20) =38357a(21) =481127a(22) =1051949a(23) =821807a(24) =2064955a(25) =8376649a(26) =13307491a(27) =917761a(28) =49342133a(29) =129187079