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 A284044 #23 Apr 02 2017 10:30:17 %S A284044 1,1,2,1,2,2,3,2,1,1,2,1,1,1,4,3,3,1,2,2,2,2,3,3,2,3,2,2,2,2,5,1,2,1, %T A284044 2,2,1,2,3,3,2,2,2,2,1,2,4,2,2,1,3,2,3,1,3,1,1,2,2,2,2,2,6,1,2,3,2,2, %U A284044 2,1,3,2,2,2,2,2,2,4,4,4,1,1,2,1,1,1,3 %N A284044 Largest positive k among all primes p < n such that n^(p-1) == 1 (mod p^k). %C A284044 a(n) > 1 iff A255920(n) > 0, i.e., iff n is a term of A273786. %e A284044 For n = 7: the maximal exponents k in the congruence 7^(p-1) == 1 (mod p^k) for p = 2, 3, 5 are 1, 1, 2, respectively. Since 2 is the largest exponent among that list, a(7) = 2. %o A284044 (PARI) a(n) = my(r=1); forprime(p=1, n-1, my(k=1); while(1, if(Mod(n, p^k)^(p-1)!=1, k--; break, k++)); if(k > r, r=k)); r %Y A284044 Cf. A255920, A258045, A268310, A273786, A278701, A282902. %K A284044 nonn %O A284044 3,3 %A A284044 _Felix Fröhlich_, Apr 02 2017