cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A324649 Numbers k such that A318458(k) (bitwise-AND of k and sigma(k)-k) is equal to k.

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%I A324649 #21 Jul 20 2021 23:48:31
%S A324649 6,20,28,36,66,72,88,100,104,114,132,150,240,258,264,272,280,304,354,
%T A324649 368,392,402,464,496,498,516,550,552,642,644,680,708,748,770,774,784,
%U A324649 786,834,836,840,860,978,1026,1032,1040,1044,1056,1062,1064,1068,1074,1092,1104,1120,1184,1232,1266,1312,1362,1376,1410,1504
%N A324649 Numbers k such that A318458(k) (bitwise-AND of k and sigma(k)-k) is equal to k.
%C A324649 Positions of zeros in A324648. Fixed points of A318458, also positions of the records in the latter.
%C A324649 Intersection with A324652 gives A324643.
%C A324649 The odd terms are: 7425, 76545, 92565, ... (A324897).
%H A324649 Antti Karttunen, <a href="/A324649/b324649.txt">Table of n, a(n) for n = 1..20000</a>
%H A324649 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%H A324649 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%t A324649 Select[Range@ 1600, BitAnd[#, DivisorSigma[1, #] - #] == # &] (* _Michael De Vlieger_, Apr 21 2019, after _Vincenzo Librandi_ at A318458 *)
%o A324649 (PARI) for(n=1,oo,if(bitand(n,sigma(n)-n)==n, print1(n, ", ")));
%Y A324649 Cf. A318458, A324648, A324652.
%Y A324649 Cf. A000396, A324643, A324897, A324898 (subsequences).
%K A324649 nonn
%O A324649 1,1
%A A324649 _Antti Karttunen_, Mar 14 2019