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 A226962 #23 Sep 06 2018 10:06:30
%S A226962 1,8,24,168,7224
%N A226962 Numbers n such that 1^n + 2^n + 3^n + ... + n^n == 4 (mod n).
%C A226962 Also, numbers n such that B(n)*n == 4 (mod n), where B(n) is the n-th Bernoulli number. Equivalently, SUM[prime p, (p-1) divides n] n/p == -4 (mod n). There are no other terms below 10^15. - _Max Alekseyev_, Aug 26 2013
%t A226962 Select[Range[10000], Mod[Sum[PowerMod[i, #, #], {i, #}], #] == 4 &]
%o A226962 (PARI) is(n)=Mod(sumdiv(n, d, if(isprime(d+1), n/(d+1))), n)==-4 \\ _Charles R Greathouse IV_, Nov 13 2013
%Y A226962 Cf. A031971.
%Y A226962 Solutions to 1^n+2^n+...+n^n == m (mod n): A005408 (m=0), A014117 (m=1), A226960 (m=2), A226961 (m=3), this sequence (m=4), A226963 (m=5), A226964 (m=6), A226965 (m=7), A226966 (m=8), A226967 (m=9), A280041 (m=19), A280043 (m=43), A302343 (m=79), A302344 (m=193).
%K A226962 nonn,more
%O A226962 1,2
%A A226962 _José María Grau Ribas_, Jun 24 2013
%E A226962 a(1)=1 prepended by _Max Alekseyev_, Aug 26 2013