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 A277340 #27 Oct 14 2016 02:23:18 %S A277340 1,2,4,7,10,92,1099,29530,281473,657892,3313964,9816013,18669155396, %T A277340 94849225930,358676424226,957439868543,1586504109310,41431374800470, %U A277340 241469610359708,256165266592379 %N A277340 Positive integers n such that n | (3^n + 11). %C A277340 No other terms below 10^15. Some larger terms: 9151612250553176993, 1401778935853533028413047652833, 5645122353966835994338815444821661584288016927879134, 313*(3^626+11)/6562567821545333606830 (280 digits). - _Max Alekseyev_, Oct 14 2016 %e A277340 3^10 + 11 = 59060 = 10 * 5906, so 10 is a term. %o A277340 (PARI) is(n)=Mod(3,n)^n==-11; \\ _Joerg Arndt_, Oct 10 2016 %o A277340 (Python) %o A277340 A277340_list = [1,2,4,7,10]+[n for n in range(11,10**6) if pow(3,n,n)==n-11] # _Chai Wah Wu_, Oct 11 2016 %Y A277340 Solutions to 3^n == k (mod n): this sequence (k=-11), A277289 (k=-7), A277288 (k=-5), A015973 (k=-2), A015949 (k=-1), A067945 (k=1), A276671 (k=2), A276740 (k=5), A277126 (k=7), A277274 (k=11). %K A277340 nonn %O A277340 1,2 %A A277340 _Seiichi Manyama_, Oct 09 2016 %E A277340 a(13)-a(14) from _Chai Wah Wu_, Oct 12 2016 %E A277340 a(15)-a(20) from _Max Alekseyev_, Oct 14 2016