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!)
A167409 Very Orderly Numbers: a number, N, is "very orderly" if the set of the divisors of N is congruent to the set {1,2,...,tau(N)} mod tau(N)+1. 6

%I

%S 1,2,5,8,11,12,17,20,23,27,29,38,41,47,52,53,57,58,59,68,71,72,76,83,

%T 87,89,101,107,113,117,118,124,131,133,137,149,158,162,164,167,173,

%U 177,178,179,188,191,197,203,218,227,233,236,237,239,243,244,247,251,257

%N Very Orderly Numbers: a number, N, is "very orderly" if the set of the divisors of N is congruent to the set {1,2,...,tau(N)} mod tau(N)+1.

%C The very orderly numbers are orderly numbers (Cf. A167408) with K = tau(N)+1

%H A. Weimholt, <a href="/A167409/b167409.txt">Table of n, a(n) for n=1..10000</a>

%t veryOrderlyQ[n_] := (If[tau = DivisorSigma[0, n]; Union[Mod[Divisors[n], tau + 1]] == Range[tau], Return[True]]; False); Select[ Range[260], veryOrderlyQ] (* _Jean-Fran├žois Alcover_, Aug 19 2013 *)

%o (PARI)

%o vo(n)=#(n=divisors(n))==#(n=Set(n%(1+#n))) & n[1]!="0"

%o for(n=1,999,vo(n)&print1(n", ")) \\ _M. F. Hasler_

%Y Cf. A167408 - Orderly Numbers

%Y Cf. A167410 - Disorderly Numbers - numbers not in A167408

%Y Cf. A167411 - Minimal K Values for the Orderly Numbers

%K nonn

%O 1,2

%A _Andrew Weimholt_, Nov 03 2009

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 March 4 02:30 EST 2021. Contains 341773 sequences. (Running on oeis4.)