A154675 - OEIS

%I #14 Dec 25 2019 04:49:40

%S 1872,7488,11700,825552,990288,1123668,1629108,3146832,3302208,

%T 4680000,6627348,7667712,8783892,15502032,16017300,16365492,17252352,

%U 25407252,32617728,42401268,42966612,54100800,66163968,71182800,73019700

%N Averages of twin prime pairs k such that k*13 and k/13 are squares.

%C Terms of this sequence must be of the form 13(6m)^2, the values for m are listed in A154775. - _M. F. Hasler_, Jan 15 2009

%H Amiram Eldar, <a href="/A154675/b154675.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = 468 A154775(n)^2 - _M. F. Hasler_, Jan 15 2009

%t lst={};Do[If[PrimeQ[n-1]&&PrimeQ[n+1],s=(n*13)^(1/2);If[Floor[s]==s,AppendTo[lst,n]]],{n,6,11!,6}];lst

%t (* ... and/or ... *)

%t lst={};Do[If[PrimeQ[n-1]&&PrimeQ[n+1],s=(n/13)^(1/2);If[Floor[s]==s,AppendTo[lst,n]]],{n,6,11!,6}];lst

%t Select[13*Range[10^3]^2, And @@ PrimeQ[# + {-1, 1}] &] (* _Amiram Eldar_, Dec 25 2019 *)

%o (PARI) for(i=1,499, isprime(468*i^2+1) && isprime(468*i^2-1) && print1(468*i^2",")) \\ _M. F. Hasler_, Jan 15 2009

%Y Cf. A154670, A154671, A154672, A154673, A154674, A154775.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Jan 13 2009

%E More terms from _M. F. Hasler_, Jan 15 2009