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!)
A171183 Numbers n such that sigmawt(n) = sigmawt(n+1), where sigmawt(n) is the sum of the divisors of n weighted by divisor multiplicity in n. 1

%I #4 Feb 11 2014 19:05:43

%S 14,957,1334,1634,2402,2685,20145,33998,42818,74918,79826,79833,84134,

%T 111506,122073,138237,147454,166934,201597,274533,289454,347738,

%U 383594,416577,440013,544334,605985,649154,655005,1060802,1642154,1674513

%N Numbers n such that sigmawt(n) = sigmawt(n+1), where sigmawt(n) is the sum of the divisors of n weighted by divisor multiplicity in n.

%H Ray Chandler, <a href="/A171183/b171183.txt">Table of n, a(n) for n=1..200</a>

%t divmult[d_, n_] := Module[{output, i}, If[d == 1, output = 1, If[d == n, output = 1, i = 0; While[Mod[n, d^(i + 1)] == 0, i = i + 1]; output = i]]; output]; dmt[n_] := Module[{divs, l}, divs = Divisors[n]; l = Length[divs]; Sum[divmult[divs[[i]], n]*divs[[i]], {i, 1, l}]]; l = {}; Do[If[dmt[i] == dmt[i + 1], l = Append[l, i]], {i, 1, 10^6}]; l

%Y See A168512 for definition of divisor multiplicity.

%K nonn

%O 1,1

%A _Joseph L. Pe_, Dec 05 2009

%E Extended by _Ray Chandler_, Dec 08 2009

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 23 08:33 EDT 2024. Contains 371905 sequences. (Running on oeis4.)