# Harvey Dubner

**Harvey Dubner** is a retired engineer and mathematician living in New Jersey, noted for his contributions to finding large prime numbers. In 1984, he and his son Robert collaborated in developing the 'Dubner cruncher', a board which used a commercial finite impulse response filter chip to speed up dramatically the multiplication of medium-sized multi-precision numbers, to levels competitive with supercomputers of the time, though nowadays his focus has changed to efficient implementation of FFT-based algorithms on personal computers.

He has found many large prime numbers of special forms: repunits, prime Fibonacci and Lucas numbers, twin primes, Sophie Germain primes, and primes in arithmetic progression.^{[1]} In 1993 he was responsible for more than half the known primes of more than two thousand digits.

Dubner was also the first to publish a paper on the first blackjack point count (The High Low Count) which is used by most blackjack card counters today. This was presented at the Fall Joint Computer Conference held in Las Vegas in 1963 at a panel titled "Using Computers in Games of Chance and Skill".

An extensive biography of Dubner, based on interviews with him and his family and highlighting the importance of his development of the "Hi-Lo" system for blackjack, is presented in an appendix to the novel *Never Split Tens* by Les Golden.

## References

**^**<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>Caldwell, Chris. "Harvey Dubner".*The Prime Pages*. Retrieved 29 April 2013.