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 A277288 #43 Apr 30 2025 09:11:18 %S A277288 1,2,14,1978,38209,4782974,9581014,244330711,365496202,1661392258, %T A277288 116084432414,288504187458218,490179448388654,802245996685561 %N A277288 Positive integers k such that k divides 3^k + 5. %C A277288 No other terms below 10^15. Some larger terms: 79854828136468902206, 3518556634988844968631084847788071912030455376274045370172567094578. - _Max Alekseyev_, Oct 14 2016 %e A277288 3^14 + 5 = 4782974 = 14 * 341641, so 14 is a term. %o A277288 (PARI) is(n)=Mod(3,n)^n==-5; \\ _Joerg Arndt_, Oct 09 2016 %o A277288 (Python) %o A277288 A277288_list = [1,2]+[n for n in range(3,10**6) if pow(3,n,n)==n-5] # _Chai Wah Wu_, Oct 09 2016 %o A277288 (Sage) %o A277288 def A277288_list(search_limit): %o A277288 n, t, r = 1, Integer(3), [1] %o A277288 while n < search_limit: %o A277288 n += 1 %o A277288 t *= 3 %o A277288 if n.divides(t+5): r.append(n) %o A277288 return r # _Peter Luschny_, Oct 10 2016 %Y A277288 Solutions to 3^n == k (mod n): A277340 (k=-11), A277289 (k=-7), this sequence (k=-5), A015973 (k=-2), A015949 (k=-1), A067945 (k=1), A276671 (k=2), A276740 (k=5), A277126 (k=7), A277274 (k=11). %K A277288 nonn,more %O A277288 1,2 %A A277288 _Seiichi Manyama_, Oct 09 2016 %E A277288 a(9) from _Joerg Arndt_, Oct 09 2016 %E A277288 a(10) from _Chai Wah Wu_, Oct 09 2016 %E A277288 a(11)-a(14) from _Max Alekseyev_, Oct 14 2016