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 A259283 #9 Sep 21 2015 20:38:15 %S A259283 165,231,273,357,399,598,715,935,1015,1105,1547,1595,1885,1886,2015, %T A259283 2093,2387,2397,2451,2465,2585,2679,2737,2821,2915,3059,3445,3913, %U A259283 3965,4123,4991,5015,5467,5719,6097,6545,7055,7189,7285,7553,7843,8555,8569,8715,8855 %N A259283 Quasi-Carmichael numbers to at least one positive base. %H A259283 Tim Johannes Ohrtmann, <a href="/A259283/b259283.txt">Table of n, a(n) for n = 1..2963</a> %e A259283 a(1) = 165 because this is the first squarefree composite number n such that at least one positive integer b except 0 exists such that for every prime factor p of n applies that p+b divides n+b (3): 165=3*5*11 and 6, 8, 14 all divide 168. %o A259283 (PARI) for(n=2, 1000000, if(!isprime(n), if(issquarefree(n), f=factor(n); b=0; until(c==0 || b==n, b++; c=0; for(i=1, #f[, 1], if((n+b)%(f[i, 1]+b)>0, c++)); if(c==0, print1(n, ", ")))))) %Y A259283 Cf. A257750, A257759, A259282. %K A259283 nonn %O A259283 1,1 %A A259283 _Tim Johannes Ohrtmann_, Jun 23 2015