login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128261 a(n) = tau(n) + (n-1)*tau(n-1). 2

%I

%S 1,3,6,9,14,14,26,18,35,31,42,28,74,30,60,65,82,40,110,44,124,88,90,

%T 54,195,79,108,114,170,66,242,68,196,136,140,149,326,78,156,164,322,

%U 90,338,92,270,274,186,104,483,153,304,210,314,114,436,228,452,232

%N a(n) = tau(n) + (n-1)*tau(n-1).

%H Andrew Howroyd, <a href="/A128261/b128261.txt">Table of n, a(n) for n = 1..1000</a>

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

%t Table[DivisorSigma[0,n]+(n-1)DivisorSigma[0,n-1],{n,60}] (* _Harvey P. Dale_, Sep 17 2020 *)

%o (PARI) a(n)={numdiv(n) + if(n > 1, (n-1)*numdiv(n-1))} \\ _Andrew Howroyd_, Aug 09 2018

%Y Row sums of A128260.

%Y Cf. A000005 (tau), A128229, A051731.

%K nonn,changed

%O 1,2

%A _Gary W. Adamson_, Feb 21 2007

%E Name changed and terms a(11) and beyond from _Andrew Howroyd_, Aug 09 2018

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 22 01:44 EDT 2020. Contains 337275 sequences. (Running on oeis4.)