Numbers k such that k^2 divides 22^k-1.

Terms

a(0) =1a(1) =3a(2) =7a(3) =21a(4) =39a(5) =273a(6) =507a(7) =3081a(8) =3549a(9) =21567a(10) =40053a(11) =78117a(12) =280371a(13) =343239a(14) =546819a(15) =1015521a(16) =2056899a(17) =2402673a(18) =5998317a(19) =6171243a(20) =7108647a(21) =8740173a(22) =12338859a(23) =14398293a(24) =18988203a(25) =27115881a(26) =41988219a(27) =43198701a(28) =47727771a(29) =55431363