Numbers k such that k^2 divides 10^k + 1.

Terms

a(0) =1a(1) =11a(2) =253a(3) =11891a(4) =35167a(5) =45023a(6) =96569a(7) =640343a(8) =1035529a(9) =1652849a(10) =2221087a(11) =19588019a(12) =30096121a(13) =48669863a(14) =74901409a(15) =88023001a(16) =89007677a(17) =104391089a(18) =143938531a(19) =154261943a(20) =308731093a(21) =395256917a(22) =674608561a(23) =725434237a(24) =920636893a(25) =1737332531a(26) =2620923899a(27) =4137081047a(28) =4183360819a(29) =5621571197