The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
Odd integers k that are not equal to A002326((A005420(k)-1)/2) where A005420(n) is the largest prime factor of 2^n - 1 and A002326(n) is the multiplicative order of 2 mod 2n+1.