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 A239723 #18 Nov 30 2014 14:51:39 %S A239723 2,1,1,2,1,0,1,0,2,0,1,2,1,2,0,6,1,0,1,0,6,2,1,2,2,0,0,0,1,2,1,2,0,2, %T A239723 2,0,1,0,2,0,1,2,1,0,0,0,1,6,0,2,0,0,1,0,0,0,0,6,1,2,1,0,0,0,2,0,1,0, %U A239723 2,2,1,2,1,0,0,6,0,0,1,0,0,2,1,2,2,0,2,0,1,2,6 %N A239723 Least number k such that n^k + (n+1)^k + ... + (n+k-1)^k is prime or 0 if no such number exists. %C A239723 a(119) = 42. Is a(n) only equal to 0, 1, 2, 6, or 42? %C A239723 a(n) = 0 is confirmed for k <= 500. See A242927. %H A239723 Derek Orr, <a href="/A239723/b239723.txt">Table of n, a(n) for n = 1..91</a> %e A239723 1^1 = 1 is not prime. 1^2+2^2 = 5 is prime. Thus a(1) = 2. %o A239723 (PARI) a(n)=for(k=1,500,if(ispseudoprime(sum(i=0,k-1,(n+i)^k)),return(k))) %o A239723 n=1;while(n<200,print1(a(n),", ");n+=1) %Y A239723 Cf. A242927. %K A239723 nonn %O A239723 1,1 %A A239723 _Derek Orr_, May 30 2014