I started this paper in ideea to present the recurrence relation defined as follows: the first term, a(0), is 13, then the n-th term is defined as a(n) = a(n–1) + 6 if n is odd and as a(n) = a(n-1) + 24, if n is even. This recurrence formula produce an amount of primes and odd numbers having very few prime factors: the first 150 terms of the sequence produced by this formula are either primes, power of primes or products of two prime factors. But then I discovered easily formulas even more interesting, for instance a(0) = 13, a(n) = a(n–1) + 10 if n is odd and a(n) = a(n-1) + 80, if n is even (which produces 16 primes in first 20 terms!). Because what seems to matter in order to generate primes for such a recurrent defined formula a(0) = 13, a(n) = a(n–1) + x if n is odd and as a(n) = a(n-1) + y, if n is even, is that x + y to be a multiple of 30 (probably the choice of the first term doesn’t matter either but I like the number 13).