Hoggatt sequence with parameter d=4.

Terms

a(0) =1a(1) =2a(2) =7a(3) =32a(4) =177a(5) =1122a(6) =7898a(7) =60398a(8) =494078a(9) =4274228a(10) =38763298a(11) =366039104a(12) =3579512809a(13) =36091415154a(14) =373853631974