A086898 a(n) = Sum_{d|n} tau(d-1).

0, 1, 2, 3, 3, 5, 4, 5, 6, 7, 4, 9, 6, 7, 9, 9, 5, 11, 6, 11, 12, 9, 4, 13, 11, 10, 10, 13, 6, 17, 8, 11, 12, 10, 11, 19, 9, 9, 12, 17, 8, 19, 8, 13, 19, 11, 4, 19, 14, 18, 13, 16, 6, 17, 15, 19, 16, 11, 4, 25, 12, 11, 20, 17, 16, 23, 8, 14, 12, 21, 8, 25, 12, 12, 21, 17, 14, 22, 8, 23, 20

Offset

1,3

Links

G. C. Greubel, Table of n, a(n) for n = 1..10000

Mathematica

a[n_] := DivisorSum[n, If[# == 1, 0, DivisorSigma[0, # - 1]] &]; Array[a, 100] (* G. C. Greubel, Dec 11 2017 *)

Crossrefs

Cf. A000005, A049822.

Sequence in context: A080391 A273494 A116922 * A123031 A271709 A369172

Adjacent sequences: A086895 A086896 A086897 * A086899 A086900 A086901

Keyword

nonn

Author

Vladeta Jovovic, Aug 23 2003

Status

approved