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:

(1)

The first few values of  generating bitwin chains are 6, 30, 660, 810, 2130, 2550, 3330, ... (OEIS A066388).

In general a chain of length  consists of  pairs of twin primes,

(2)

Bitwin chains can also be viewed as consisting of two related Cunningham chains of the first and second kinds,

(3)

P. Jobling (1999) found the largest known chain of length six,

(4)

where  to 6.

REFERENCES:

Jobling, P. "A BiTwin Chain of Length 6 Discovered." 4 Oct 1999. http://listserv.nodak.edu/scripts/wa.exe?A2=ind9910&L=NMBRTHRY&P=151.

Lifchitz, H. "New Chains of Prime Numbers." http://ourworld.compuserve.com/homepages/hlifchitz/Henri/us/NouvChPus.htm.

Sloane, N. J. A. Sequence A066388 in "The On-Line Encyclopedia of Integer Sequences."