Re: [math-fun] Digital silliness

For a number n, let f(n) be the set of numbers gotten by splitting n^2 at the 0 digits. For example

29648^2 = 879003904

so f(29648) = { 4, 39, 879 }

Let S be the smallest set of numbers containing 2 and fixed by f. What is the largest element of S?

[ meaning "if s in S , then f(s) is a subset of S " ] in case anyone is still interested ... i completed a depth-first search through 50 generations. the largest number arising within 50 generations has 110 decimal digits: 3457746548572498971631711458544819351439214287725631661- 1563654569796733285181233292965618589219724572135111824 i haven't had the chance to code breadth-first search or a hybrid approach. mike