Crystal ball sequence for A_7 lattice.

Terms

a(0) =1a(1) =57a(2) =869a(3) =6637a(4) =33111a(5) =124223a(6) =380731a(7) =1004307a(8) =2360501a(9) =5064013a(10) =10089705a(11) =18912785a(12) =33681595a(13) =57426435a(14) =94307855a(15) =149907847a(16) =231567369a(17) =348773633a(18) =513600589a(19) =741206037a(20) =1050388799a(21) =1464209383