A356260 - OEIS

%I #10 Aug 03 2022 12:40:09

%S 11,41,101,107,197,311,461,521,827,1061,1277,1451,1487,1871,2027,2141,

%T 2801,3251,3671,4091,4547,5651,5657,6197,6791,6827,7307,7457,8837,

%U 9011,9041,9437,9857,10007,10301,10457,11777,12041,12251,12611,13691,13721,13997,14321,14387,15287,15641,17027,17747

%N Lower twin primes p such that (p^2 + (p+2)^2)/10 is prime.

%H Robert Israel, <a href="/A356260/b356260.txt">Table of n, a(n) for n = 1..10000</a>

%e a(3) = 101 is a term because 101 and 103 are primes and (101^2 + 103^2)/10 = 2081 is prime.

%p P:= select(isprime, {seq(i,i=3..10^5,2)}):

%p T:=P intersect map(`-`,P,2):

%p filter:= proc(t) local s; s:= (t^2 + (t+2)^2)/10; s::integer and isprime(s) end proc:

%p sort(convert(select(filter, T),list));

%t Select[Prime[Range[2000]], And @@ PrimeQ[{# + 2, (#^2 + (# + 2)^2)/10}] &] (* _Amiram Eldar_, Aug 01 2022 *)

%Y Cf. A001359.

%K nonn

%O 1,1

%A _J. M. Bergot_ and _Robert Israel_, Jul 31 2022