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.
%I A309003 #22 Apr 22 2024 13:48:07 %S A309003 3240392401,13577445505,14446721521,84127131361,203340265921, %T A309003 241420757761,334797586201,381334973041,461912170321,1838314142785, %U A309003 3636869821201,10285271821441,17624045440981,18773053896961,20137015596061,24811804945201,26863480687681,35598629998801 %N A309003 Carmichael numbers divisible by the sum of their prime factors, sopfr (A001414). %C A309003 Intersection of A002997 and A308643. %C A309003 Intersection of A002997 and A036844. %H A309003 Amiram Eldar, <a href="/A309003/b309003.txt">Table of n, a(n) for n = 1..10000</a> (calculated using data from Claude Goutier) %H A309003 Claude Goutier, <a href="http://www-labs.iro.umontreal.ca/~goutier/OEIS/A055553/">Compressed text file carm10e22.gz containing all the Carmichael numbers up to 10^22</a>. %H A309003 <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers</a>. %e A309003 3240392401 = 29*37*41*73*1009, A001414(3240392401)=1189 = 29*41. %o A309003 (PARI) sopfr(f) = f[, 1]~*f[, 2]; %o A309003 isCarmichael(n, f)= bittest(n, 0) && !for(i=1, #f~, (f[i, 2]==1 && n%(f[i, 1]-1)==1)||return) && (#f~>1); %o A309003 isok(n) = my(f=factor(n)); isCarmichael(n, f) && !(n % sopfr(f)); \\ _Michel Marcus_, Jul 07 2019 %Y A309003 Cf. A002997, A001414, A036844, A046347, A308643. %K A309003 nonn %O A309003 1,1 %A A309003 _David James Sycamore_, Jul 05 2019