%I #17 Dec 27 2019 11:55:03

%S 8,15,23,24,71,80,104,128,159,216,231,264,288,303,336,344,455,495,528,

%T 543,560,608,624,680,744,816,840,879,896,1016,1104,1311,1415,1440,

%U 1464,1520,1584,1599,1751,1871,1896,1920,1976,2015,2016,2055,2088,2103,2175

%N Numbers k such that k*(k+1)/4 - 1 and k*(k+1)/4 + 1 are twin primes.

%C The twin primes are = (sum of numbers from 1 to k)/2 -1 and +1.

%H Amiram Eldar, <a href="/A105174/b105174.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harvey P. Dale)

%e 8*9/4=18, 17 and 19 twin primes so a(1)=8

%e 15*16/4=60, 59 and 61 twin primes so a(2)=15

%t Select[Range[2200],AllTrue[(#(#+1))/4+{1,-1},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Aug 01 2015 *)

%Y Cf. A001097, A001359, A006512, A165966.

%K nonn

%O 1,1

%A _Pierre CAMI_, Apr 11 2005

%E More terms from _Zak Seidov_, Oct 07 2009