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A139432
a(0)=0. For n>=1, a(n) = a(n-1) - d(n) if a(n-1) >= d(n); a(n) = a(n-1) + d(n) if a(n-1) < d(n); where d(n) is the number of positive divisors of n.
2
0, 1, 3, 1, 4, 2, 6, 4, 0, 3, 7, 5, 11, 9, 5, 1, 6, 4, 10, 8, 2, 6, 2, 0, 8, 5, 1, 5, 11, 9, 1, 3, 9, 5, 1, 5, 14, 12, 8, 4, 12, 10, 2, 0, 6, 0, 4, 2, 12, 9, 3, 7, 1, 3, 11, 7, 15, 11, 7, 5, 17, 15, 11, 5, 12, 8, 0, 2, 8, 4, 12, 10, 22, 20, 16, 10, 4, 0, 8, 6, 16, 11, 7, 5, 17, 13, 9, 5, 13, 11, 23, 19
OFFSET
0,3
COMMENTS
a(A139433(n)) = 0.
LINKS
MATHEMATICA
Join[{a = 0}, Table[If[a < (x = DivisorSigma[0, n]), a += x, a -= x]; a, {n, 91}]] (* Jayanta Basu, Jun 06 2013 *)
CROSSREFS
Cf. A139433.
Sequence in context: A066899 A309636 A309650 * A363653 A202154 A115208
KEYWORD
nonn
AUTHOR
Leroy Quet, Apr 21 2008
EXTENSIONS
More terms from Sean A. Irvine, Dec 02 2009
STATUS
approved