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A202275
Differences between A074753 (number of integers k such that sigma(k) <= n) and A202276 (number of integers k <= n such that sigma(x) = k has no solution); sigma = A000203.
4
1, 0, 1, 2, 1, 2, 3, 4, 3, 2, 1, 3, 4, 5, 6, 5, 4, 6, 5, 6, 5, 4, 3, 6, 5, 4, 3, 4, 3, 4, 6, 8, 7, 6, 5, 6, 5, 6, 7, 8, 7, 10, 9, 10, 9, 8, 7, 10, 9, 8, 7, 6, 5, 7, 6, 8, 9, 8, 7, 10, 9, 10, 11, 10, 9, 8, 7, 8, 7, 6, 5, 10, 9, 10, 9, 8, 7, 8, 7, 9, 8, 7, 6, 9
OFFSET
1,4
COMMENTS
Conjectures: Max a(n) = 15 for n = 195, 403, 434. For n >= 687, a(n) < 0.
First term < 0: a(538) = -1.
LINKS
FORMULA
a(n) = A074753(n) - A202276(n).
KEYWORD
sign
AUTHOR
Jaroslav Krizek, Dec 25 2011
STATUS
approved