cp's OEIS Frontend

A156021 Numbers k such that k^1 + k^2 + k^3 + k^4 -+ 1 are twin primes.

%I A156021 #16 Sep 08 2022 08:45:41
%S A156021 1,2,12,30,44,50,63,74,110,165,177,222,239,254,327,492,519,804,942,
%T A156021 954,1007,1343,1352,1520,1770,2375,2450,2658,2795,2945,2994,3075,3332,
%U A156021 3527,3548,3803,3915,3935,4025,4653,4704,4785,4808,4862,5270,5310,5364,5370
%N A156021 Numbers k such that k^1 + k^2 + k^3 + k^4 -+ 1 are twin primes.
%H A156021 Amiram Eldar, <a href="/A156021/b156021.txt">Table of n, a(n) for n = 1..10000</a>
%e A156021 2 is a term since 2 + 2^2 + 2^3 + 2^4 - 1 = 29 and 2 + 2^2 + 2^3 + 2^4 + 1 = 31 are twin primes.
%t A156021 lst={};Do[p=(n^1+n^2+n^3+n^4);If[PrimeQ[p-1]&&PrimeQ[p+1],AppendTo[lst,n]],{n,8!}];lst
%o A156021 (Magma) [n: n in [1..6*10^3] | IsPrime(n^4+n^3+n^2+n-1) and IsPrime(n^4+n^3+n^2+n+1)]; // _Vincenzo Librandi_, Dec 26 2015
%Y A156021 Cf. A125964, A156018.
%K A156021 nonn,easy
%O A156021 1,2
%A A156021 _Vladimir Joseph Stephan Orlovsky_, Feb 01 2009