login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A057921 d(n+1) divides d(n), where d(n) is number of positive divisors of n. 4

%I #9 May 29 2015 15:13:16

%S 2,6,10,12,14,18,21,22,26,28,30,33,34,38,40,42,44,46,52,54,56,57,58,

%T 60,66,70,72,75,78,80,82,84,85,86,88,90,93,94,96,98,102,104,105,106,

%U 108,110,112,114,116,118,122,126,128,130,132,133,135,136,138,140,141,142

%N d(n+1) divides d(n), where d(n) is number of positive divisors of n.

%H Ivan Neretin, <a href="/A057921/b057921.txt">Table of n, a(n) for n = 0..10000</a>

%e 10 is included because d(11) = 2 divides d(10) = 4.

%t Select[Range@150, Divisible @@ DivisorSigma[0, {#, # + 1}] &] (* _Ivan Neretin_, May 29 2015 *)

%Y Cf. A057922, A005237.

%K nonn

%O 0,1

%A _Leroy Quet_, Nov 11 2000

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 19 02:28 EDT 2024. Contains 371782 sequences. (Running on oeis4.)