Sum of the entries in the character table of the alternating group A_n.

Terms

a(0) =1a(1) =1a(2) =3a(3) =8a(4) =19a(5) =52a(6) =140a(7) =479a(8) =1464a(9) =5596a(10) =19334a(11) =78841a(12) =305406a(13) =1295435a(14) =5527265a(15) =24403208a(16) =112338932a(17) =517908324a(18) =2531226446a(19) =12216601247a(20) =62626424572a(21) =316570510625