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 A084741 #13 Oct 30 2017 04:32:30 %S A084741 3,7,13,521,31,43,0,73,9091,13421,19141,157,7027567,211,241,22796593, %T A084741 307,274019342889240109297,152381,421,463,39700406579747,183458857, %U A084741 601,135938684703251,0,757,574995877 %N A084741 Smallest prime of the form (n^k+1)/(n+1), or 0 if no such prime exists. %C A084741 When n is a power (greater than 2) of a prime, then (n^k+1)/(n+1) will usually be composite for all k, which is the case for n = 8, 27, 32, 64, 125. The next term, a(30), is a 204-digit number. - _T. D. Noe_, Jan 22 2004 %H A084741 H. Dubner and T. Granlund, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL3/DUBNER/dubner.html">Primes of the Form (b^n+1)/(b+1)</a>, J. Integer Sequences, 3 (2000), #P00.2.7. %H A084741 R. G. Wilson, v, <a href="/A084740/a084740.pdf">Letter to N. J. A. Sloane, circa 1991.</a> %e A084741 a(7)= 43 = (7^3 +1 )/(7+1) = 1 - 7 + 7^2 is a prime. %Y A084741 Cf. A084742 (least k such that (n^k+1)/(n+1) is prime). %K A084741 nonn %O A084741 2,1 %A A084741 _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 15 2003 %E A084741 More terms from _T. D. Noe_, Jan 22 2004