Even composite integers m such that A006190(m)^2 == 1 (mod m).

Terms

a(0) =4a(1) =8a(2) =16a(3) =68a(4) =1208a(5) =1424a(6) =3056a(7) =3824a(8) =3928a(9) =20912a(10) =52174a(11) =63716a(12) =88708a(13) =123148a(14) =161872a(15) =582224a(16) =887566a(17) =17083292a(18) =18900412a(19) =34648888a(20) =39991684a(21) =44884912a(22) =51390736a(23) =103170448a(24) =107825236a(25) =132238514a(26) =279900272a(27) =686071244a(28) =769252508a(29) =3251623346