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.

A291602 Composite integers k satisfying 2^d == 2^(k/d) (mod k) for all d|k and that are not Super-Poulet (A050217).

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%I A291602 #28 Apr 23 2024 11:21:15
%S A291602 1105,13981,68101,137149,149281,158369,266305,285541,423793,617093,
%T A291602 625921,852841,1052503,1052929,1104349,1128121,1306801,1746289,
%U A291602 2940337,3048841,3828001,4072729,4154161,4209661,4682833,6183601,6236473,6617929,7803769,9106141,11157721,11644921,12096613,12932989,13554781
%N A291602 Composite integers k satisfying 2^d == 2^(k/d) (mod k) for all d|k and that are not Super-Poulet (A050217).
%C A291602 The set difference of A291601 and A050217.
%C A291602 Terms that are Carmichael numbers (A002997) are given by A291612. - _Altug Alkan_, Aug 27 2017
%H A291602 Amiram Eldar, <a href="/A291602/b291602.txt">Table of n, a(n) for n = 1..10000</a>
%o A291602 (PARI) is(k) = {if(k == 1 || !(k%2) || isprime(k), return(0)); my(issp = 1); fordiv(k, d, if(Mod(2, d)^d != 2, issp = 0; break)); if(!issp, fordiv(k, d, if(d^2 <= k && Mod(2, k)^d != Mod(2, k)^(k/d), return(0))); 1, 0);} \\ _Amiram Eldar_, Apr 22 2024
%Y A291602 Cf. A001567, A050217, A291601.
%K A291602 nonn
%O A291602 1,1
%A A291602 _Max Alekseyev_, Aug 27 2017