a(n) = F(n)^2 + F(n+1)^2 + F(n+2)^2, where F(n) denotes the n-th Fibonacci number.

Terms

a(0) =2a(1) =6a(2) =14a(3) =38a(4) =98a(5) =258a(6) =674a(7) =1766a(8) =4622a(9) =12102a(10) =31682a(11) =82946a(12) =217154a(13) =568518a(14) =1488398a(15) =3896678a(16) =10201634a(17) =26708226a(18) =69923042a(19) =183060902a(20) =479259662a(21) =1254718086a(22) =3284894594a(23) =8599965698a(24) =22515002498a(25) =58945041798a(26) =154320122894a(27) =404015326886