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A073462
Number of solutions to phi(x) - pi(x) = n.
2
6, 8, 5, 9, 3, 3, 6, 6, 1, 5, 5, 3, 3, 5, 3, 4, 6, 1, 5, 7, 5, 2, 4, 2, 1, 5, 5, 1, 4, 2, 2, 7, 3, 4, 4, 4, 2, 5, 1, 4, 1, 6, 4, 5, 3, 2, 4, 2, 3, 6, 1, 6, 3, 6, 3, 1, 1, 2, 5, 4, 3, 3, 4, 2, 0, 4, 3, 4, 3, 1, 2, 6, 4, 4, 0, 5, 5, 4, 2, 6, 4, 3, 2, 5, 5, 1, 1, 9, 1, 3, 1, 4, 4, 3, 3, 2, 4, 4, 3, 2, 4
OFFSET
-1,1
COMMENTS
Although Pi takes all values, solutions are not guaranteed since nontotient numbers exist.
FORMULA
a(n)=Card[{x; A000010(x)-A000720(x)=n}]
EXAMPLE
n=-1: 6 solutions = {6,12,18,24,42,60}, a(-1)=6; n=5: for 6 terms of {11,32,34,50,70,150}, phi(#) - pi(#) = 6 holds, so a(5)=6; n=63: no solution was found at x <= 1000000.
KEYWORD
nonn
AUTHOR
Labos Elemer, Aug 02 2002
STATUS
approved