A122564 - OEIS

%I #6 May 17 2021 14:25:43

%S 3,5,11,13,59,61,71,73,107,109,179,181,191,193,227,229,239,241,311,

%T 313,347,349,419,421,431,433,599,601,659,661,827,829,1019,1021,1031,

%U 1033,1091,1093,1151,1153,1319,1321,1427,1429,1451,1453,1487,1489,1607,1609

%N Twin primes of form 4k-1, 4k+1.

%H Harvey P. Dale, <a href="/A122564/b122564.txt">Table of n, a(n) for n = 1..1000</a>

%e a(3)=11=4*3-1, a(4)=13=4*3+1

%p i:=1:for k from 1 to 600 do if isprime(4*k-1) and isprime(4*k+1) then a[i]:=4*k-1:a[i+1]:=4*k+1: i:=i+2 fi od: seq(a[n],n=1..i-1);

%t Select[Partition[Prime[Range[300]],2,1],#[[2]]-#[[1]]==2&&Divisible[ Mean[ #],4]&]//Flatten (* _Harvey P. Dale_, May 17 2021 *)

%Y Cf. A001097.

%K nonn

%O 1,1

%A _Miklos Kristof_, Sep 21 2006