Retorts

Honouring a Number Theorist

The most prolific mathematician of the 20th century, Paul Erdos, described the mathematician species as a device for turning coffee into theorems. Judging by the cup stains on Alan Robert Boyd's letters to me, Alan, who died recently, practised a lot of number theory.

Just before Christmas, Alan requested a disk of Acorn computer programs from me; he wanted to hire a computer. Although I did a few short calculations for Alan, he usually produced his own printouts, photocopying one side of the paper and copying dozens of columns of figures by hand in pen or pencil on the reverse side. He was the human printer computer.

Alan studied sequences of integers. Hati numbers are integers 2^a .3^b.N where a+b is even, and N is a whole number not divisible by 2 or 3.

A few Hati numbers are:

1 = 20 .30		a+b= 0
4 = 22		a+b = 2
6 = 21 .31		a+b= 2
9 = 32		a+b= 2
20 = 22 .5		a+b=2

On my kitchen wall Alan gave me a colour-coded array of Hati numbers up to 100. Alan taught me about Panarithmic numbers and Boyd numbers and I introduced him to primitive roots. Alan arrived on the doorstep of my Newtown, Wellington, bedsit flat from Dunedin. He may have seen my ads in New Zealand Science Monthly and was referred to me by the Maths Department at Canterbury University.

Every year he travelled to the North Island for NZ Scrabble championships. And he visited contacts in Wellington, including a brother in Lower Hutt and myself.

Alan was the first pedestrian killed on NZ roads this year, on 1 January 1999. It is presumed that he was the victim of a hit-and-run driver.

Don S. McDonald, Wellington