Crystal ball sequence for E_6 lattice.

Terms

a(0) =1a(1) =73a(2) =1135a(3) =7831a(4) =34147a(5) =111835a(6) =301645a(7) =707365a(8) =1492669a(9) =2900773a(10) =5276899a(11) =9093547a(12) =14978575a(13) =23746087a(14) =36430129a(15) =54321193a(16) =79005529a(17) =112407265a(18) =156833335a(19) =215021215a(20) =290189467a(21) =386091091