298389

Appears in sequences

• Wieferich numbers (1): n > 1 such that 2^A000010(n) == 1 (mod n^2).at n=19A077816
• Second elementary symmetric function of the first n terms of (1,3,9,27,81,...).at n=5A203243
• Numbers n > 1 such that 2^m == 1 (mod n^2), where m = A002326((n-1)/2).at n=15A265630
• Numbers n > 1 such that 2^lambda(n) == 1 (mod n^2), where lambda(n) is the Carmichael lambda function (A002322).at n=16A291961