A128261 a(n) = tau(n) + (n-1)*tau(n-1).

1, 3, 6, 9, 14, 14, 26, 18, 35, 31, 42, 28, 74, 30, 60, 65, 82, 40, 110, 44, 124, 88, 90, 54, 195, 79, 108, 114, 170, 66, 242, 68, 196, 136, 140, 149, 326, 78, 156, 164, 322, 90, 338, 92, 270, 274, 186, 104, 483, 153, 304, 210, 314, 114, 436, 228, 452, 232

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1000

Example

a(5) = 14 = (5 + 4 + 0 + 4 + 1), where (5, 4, 0, 4, 1) = row 5 of A128260.

Mathematica

Table[DivisorSigma[0, n]+(n-1)DivisorSigma[0, n-1], {n, 60}] (* Harvey P. Dale, Sep 17 2020 *)

Prog

(PARI) a(n)={numdiv(n) + if(n > 1, (n-1)*numdiv(n-1))} \\ Andrew Howroyd, Aug 09 2018

Crossrefs

Row sums of A128260.

Cf. A000005 (tau), A128229, A051731.

Sequence in context: A242339 A086838 A161669 * A310162 A310163 A310164

Adjacent sequences: A128258 A128259 A128260 * A128262 A128263 A128264

Keyword

nonn

Author

Gary W. Adamson, Feb 21 2007

Extensions

Name changed and terms a(11) and beyond from Andrew Howroyd, Aug 09 2018

Status

approved