262177

Appears in sequences

• a(n) = 2^(n+1) + 2*n - 1.at n=17A131898
• a(n) = Sum_{d|n} d^(2*d + 1).at n=3A283533
• Square array A(n,k), n >= 1, k >= 0, read by antidiagonals, where A(n,k) is Sum_{d|n} d^(k*d+1).at n=18A308704
• If the Collatz trajectory of n reaches 1, say after k steps, and there is an integer m > n such that T^i(m) and T^i(n) have the same parity for i = 0..k (where T^i denotes the i-th iterate of the Collatz map A006370), then a(n) is the least such m, otherwise a(n) is -1.at n=32A348094