In how many ways can we write 100 as a sum a

_{1}+ a_{2}+ ... + a_{k}, where the a_{i}are positive integers and a_{i}is at least twice as big as a_{i-1}? (note: k can possibly equal 1, 2, 3, ...)Source: Suggested by John Renze (Northwestern); is related to Steenrod algebras, see: Steenrod, N. and Epstein, D.,© Copyright 2001 Stan Wagon. Reproduced with permission.Cohomology Operations, Princeton University Press, 1962.

20 Apr 2001