Upper bound arising in Hadwiger's conjecture.

Terms

a(0) =0a(1) =0a(2) =110a(3) =1054a(4) =7097a(5) =41201a(6) =220171a(7) =1115862a(8) =5451131a(9) =25919515a(10) =120721773a(11) =553162595a(12) =2501388936a(13) =11188504443a(14) =49589159037a(15) =218081007181a(16) =952654230982