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.

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

N. J. A. Sloane, Table of n, a(n) for n = 0..10000

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

Adjacent sequences: A139429 A139430 A139431 * A139433 A139434 A139435

Keyword

nonn

Author

Leroy Quet, Apr 21 2008

Extensions

More terms from Sean A. Irvine, Dec 02 2009

Status

approved