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A243983
Sum of twin divisors of n.
2
0, 0, 4, 6, 0, 4, 0, 6, 4, 0, 0, 16, 0, 0, 9, 6, 0, 4, 0, 6, 4, 0, 0, 24, 0, 0, 4, 6, 0, 9, 0, 6, 4, 0, 12, 16, 0, 0, 4, 24, 0, 4, 0, 6, 9, 0, 0, 24, 0, 0, 4, 6, 0, 4, 0, 6, 4, 0, 0, 43, 0, 0, 20, 6, 0, 4, 0, 6, 4, 12, 0, 24, 0, 0, 9, 6, 0, 4, 0, 24, 4, 0, 0, 42, 0, 0, 4, 6, 0, 9
OFFSET
1,3
COMMENTS
See A243865 for definition of twin divisor.
LINKS
FORMULA
a(n) = A000203(n) - A243984(n).
EXAMPLE
The positive divisors of 40 are 1, 2, 4, 5, 8, 10, 20, 40. Of these, 2, 4, 8, 10, are twin divisors. So a(40) = the sum of these divisors, which is 24.
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved