Composites c for which an integer 1 < k < c exists such that (c-k)! == -1 (mod c).

Terms

a(0) =25a(1) =121a(2) =169a(3) =437a(4) =551a(5) =667a(6) =721a(7) =1037a(8) =1159a(9) =1273a(10) =1349a(11) =1403a(12) =1541a(13) =1769a(14) =1943a(15) =2209a(16) =2329a(17) =2363a(18) =2419a(19) =3071a(20) =3713a(21) =4087a(22) =5041a(23) =5111a(24) =7313a(25) =8357a(26) =8479a(27) =9017a(28) =11357a(29) =11983