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 A191975 #16 Aug 18 2019 16:35:25 %S A191975 1,2,6,42,330,235290,310800,1863851053628494074457830 %N A191975 Least common multiple of all p-1, where prime p divides the n-th primary pseudoperfect number A054377(n). %C A191975 a(n) is a factor of any exponent k > 0 such that 1^k + 2^k + ... + p^k == 1 (mod p), where p = A054377(n). %H A191975 J. Sondow and K. MacMillan, <a href="http://www.emis.de/journals/INTEGERS/papers/l34/l34.Abstract.html">Reducing the Erdős-Moser equation 1^n + 2^n + ... + k^n = (k+1)^n modulo k and k^2</a>, Integers 11 (2011), #A34. %F A191975 a(n) = lcm(p-1 : prime p | A054377(n)). %e A191975 A054377(3) = 42 = 2*3*7, so a(3) = lcm(2-1, 3-1, 7-1) = lcm(1,2,6) = 6. %Y A191975 Cf. A054377. %K A191975 nonn,more,hard %O A191975 1,2 %A A191975 _Kieren MacMillan_, Jun 20 2011