Numbers k such that Sum_{j=1..k} (-j)^j == 1 (mod k).

Terms

a(0) =1a(1) =2a(2) =30a(3) =33a(4) =37a(5) =83a(6) =149a(7) =262a(8) =4030a(9) =31969a(10) =140225a(11) =182730a(12) =724754a(13) =2337094a(14) =3985753a(15) =4195221a(16) =4541725