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!)
A347938 Primitive terms of A347935: terms of A347935 that are not multiples of other terms of A347935. 2

%I

%S 60,72,108,168,252,264,280,312,396,400,468,588,612,684,816,828,880,

%T 912,924,1040,1044,1092,1104,1116,1232,1332,1360,1392,1428,1456,1476,

%U 1520,1548,1568,1596,1692,1716,1840,1890,1908,1932,2124,2196,2200,2244,2288,2320

%N Primitive terms of A347935: terms of A347935 that are not multiples of other terms of A347935.

%C Since any positive multiple of a term of A347935 is also a term of A347935, the sequence A347935 consists of the positive multiple of this sequence.

%H Amiram Eldar, <a href="/A347938/b347938.txt">Table of n, a(n) for n = 1..10000</a>

%e The first 10 terms of A347935 are 60, 72, 108, 120, 144, 168, 180, 216, 240, 252. 120, 180 and 240 are multiples of 60, 144 is a multiple of 72, and 216 is a multiple of 108 and therefore they are not terms of this sequence. So, this sequence begins with 60, 72, 108, 168, 252.

%t abQ[n_] := DivisorSigma[1, n] > 2*n; s[n_] := DivisorSum[n, # &, abQ[#] &]; q[n_] := s[n] > 2*n && AllTrue[Most @ Divisors[n], ! q[#] &]; Select[Range[3000], q]

%Y Subsequence of A005101 and A347935.

%Y Cf. A071395, A091191, A187795.

%K nonn

%O 1,1

%A _Amiram Eldar_, Sep 20 2021

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 September 28 12:47 EDT 2022. Contains 357070 sequences. (Running on oeis4.)