The Writings of E. Emmanuel Macaulay http://mathmeth.com/eem/ The Natural Fold http://mathmeth.com/eem/foldn.pdf The natural unfold http://mathmeth.com/eem/unfoldn.pdf The list unfold http://mathmeth.com/eem/unfoldl.pdf Project Euler, Problem 1 http://mathmeth.com/eem/euler1.pdf