# acm.uva.es
# ipsc.ksp.sk
# algoritmus.org/index.php

# http://www.research.att.com/~njas/sequences/

# http://www.research.att.com/~njas/sequences/ ["aici":http://www.research.att.com/~njas/sequences/]

# http://www.ics.uci.edu/~eppstein/junkyard/euler/