a(n) = (2n+1)^(2n+1) mod 2^(2n+1).

Terms

a(0) =1a(1) =3a(2) =21a(3) =119a(4) =329a(5) =339a(6) =1533a(7) =2031a(8) =67857a(9) =68491a(10) =1472837a(11) =7105255a(12) =20933977a(13) =91061443a(14) =344607757a(15) =137379807a(16) =942687265a(17) =22093239035a(18) =115763405909a(19) =23058549975a(20) =581930881897