Least number k >= 0 such that n! - k is a perfect power.

Terms

a(0) =0a(1) =1a(2) =2a(3) =8a(4) =20a(5) =44a(6) =127a(7) =320a(8) =476a(9) =3584a(10) =12311a(11) =4604a(12) =74879a(13) =414119a(14) =2071775a(15) =5703551a(16) =11551671a(17) =45680444a(18) =442548224a(19) =1960632176a(20) =2657058876a(21) =24923993276a(22) =130518272975