In how many ways can we write 100 as a sum a1 + a2 + ... + ak, where the ai are positive integers and ai is at least twice as big as ai-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., Cohomology Operations, Princeton University Press, 1962.© Copyright 2001 Stan Wagon. Reproduced with permission.