29

This number is a prime.

Just showing those entries submitted by 'Petrov': (Click here to show all)

29 + 2*Hn (where Hn stands for the n-th centered hexagonal number) yields 30 primes for n = 0 to 29. Recall that 29 + 2*n^2 (i.e., twice the n-th square number) yields 29 primes for n = 0 to 28. [Petrov]