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 A217070 #17 Jul 08 2025 15:01:39 %S A217070 2,3,5,7,34,37,43,59,72,94,98,110,133,149,151,159,190,207,219,221,251, %T A217070 260,264,267,282,286,291,319,355,363,373,382,397,398,402,406,408,412, %U A217070 436,442,486,489,507,542,544,552,553,582,585,592,603,610,614,634,643 %N A217070 Numbers k such that (k^13-1)/(k-1) is prime. %H A217070 Vincenzo Librandi, <a href="/A217070/b217070.txt">Table of n, a(n) for n = 1..1000</a> %t A217070 Select[Range[2, 1000], PrimeQ[(#^13 - 1)/(# - 1)] &] (* _T. D. Noe_, Sep 26 2012 *) %o A217070 (Magma) [n: n in [2..1000] |IsPrime((n^13 - 1) div (n - 1))]; // _Vincenzo Librandi_, Sep 28 2012 %o A217070 (PARI) is(n)=isprime(polcyclo(13,n)) \\ _Charles R Greathouse IV_, Apr 28 2015 %Y A217070 Cf. A002384, A049409, A100330, A162862, A217071-A217089. %K A217070 nonn,easy %O A217070 1,1 %A A217070 _Tim Johannes Ohrtmann_, Sep 26 2012