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 A237877 #22 Sep 27 2015 02:42:01 %S A237877 1,2,9,11,17,48,57,427,533,1661,2161,4441,5428,41628,171441,411735, %T A237877 555716,1278525,4292829,5174373,8758407,680133057 %N A237877 Numbers n such that n | A067439(n). %C A237877 a(19) > 3000000. - _Giovanni Resta_, Feb 17 2014 %C A237877 a(23) > 4 * 10^9. - _Hiroaki Yamanouchi_, Sep 27 2015 %e A237877 48 is coprime to 1, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47. When 48 is divided by these numbers the remainders are 0, 3, 6, 4, 9, 14, 10, 2, 23, 19, 17, 13, 11, 7, 5, 1. Their sum is 144 and 144 / 48 = 3. %p A237877 with(numtheory);P:=proc(q) local i,n,t; for n from 1 to q do t:=0; %p A237877 for i from 2 to n-1 do if gcd(i,n)=1 then t:=t+(n mod i); fi; od; %p A237877 if type(t/n,integer) then print(n); fi; od; end: P(10^6); %o A237877 (PARI) is(n)=sum(i=1, n-1, if(gcd(n, i)==1, n%i))%n==0 \\ _Charles R Greathouse IV_, Nov 06 2014 %Y A237877 Cf. A067439. %K A237877 nonn,more %O A237877 1,2 %A A237877 _Paolo P. Lava_, Feb 14 2014 %E A237877 a(14) from _Michel Marcus_, Feb 17 2014 %E A237877 a(15)-a(18) from _Giovanni Resta_, Feb 17 2014 %E A237877 a(19)-a(22) from _Hiroaki Yamanouchi_, Sep 27 2015