a(n) is the largest prime factor of n^n + n.

Terms

a(0) =2a(1) =3a(2) =5a(3) =13a(4) =313a(5) =101a(6) =181a(7) =5419a(8) =21523361a(9) =52579a(10) =212601841a(11) =57154490053a(12) =815702161a(13) =100621a(15) =4562284561a(16) =52548582913a(18) =211573a(21) =9299179