Golden Triangle sums: a(n)=a(n-4)+A001654(n) with a(0)=0, a(1)=1, a(2)=2 and a(3)=6.

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =15a(5) =41a(6) =106a(7) =279a(8) =729a(9) =1911a(10) =5001a(11) =13095a(12) =34281a(13) =89752a(14) =234971a(15) =615165a(16) =1610520a(17) =4216400a(18) =11038675a(19) =28899630a(20) =75660210a(21) =198081006a(22) =518582802a(23) =1357667406a(24) =3554419410a(25) =9305590831a(26) =24362353076a(27) =63781468404