A bitwin chain of length one consists of two pairs of twin primes with the property that they are related by being of the form: (n - 1, n + 1) and (2n - 1, 2n + 1). The first few values of n generating bitwin chains are 6, 30, 660, 810, 2130, 2550, 3330, ... (OEIS A066388). In general a chain of length i consists of i + 1 pairs of twin primes, (n - 1, n + 1), (2n - 1, 2n + 1), ..., (2^i·n - 1, 2^i·n + 1). Bitwin chains can also be viewed as consisting of two related Cunningham chains of the first and second kinds, (n - 1, 2n - 1, 4n - 1, ...) and (n + 1, 2n + 1, 4n + 1, ...).

Cunningham chain | twin primes