Initial data commit

Task/Mertens-function/Factor/mertens-function.factor

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+USING: formatting grouping io kernel math math.extras
+math.ranges math.statistics prettyprint sequences ;
+
+! Take the cumulative sum of the mobius sequence to avoid
+! summing lower terms over and over.
+: mertens-upto ( n -- seq ) [1,b] [ mobius ] map cum-sum ;
+
+"The first 199 terms of the Mertens sequence:" print
+199 mertens-upto " " prefix 20 group
+[ [ "%3s" printf ] each nl ] each nl
+
+"In the first 1,000 terms of the Mertens sequence there are:"
+print 1000 mertens-upto
+[ [ zero? ] count bl pprint bl "zeros." print ]
+[
+    2 <clumps> [ first2 [ 0 = not ] [ zero? ] bi* and ] count bl
+    pprint bl "zero crossings." print
+] bi