For any n > 0, let E_n be the variant of Van Eck's sequence where values are taken mod n; if E_n is eventually periodic, then a(n) is the length of its transient part; otherwise a(n) = -1.

A352641

For any n > 0, let E_n be the variant of Van Eck's sequence where values are taken mod n; if E_n is eventually periodic, then a(n) is the length of its transient part; otherwise a(n) = -1.