# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a162864 Showing 1-1 of 1 %I A162864 #7 Dec 31 2024 18:09:33 %S A162864 6,12,18,30,36,42,60,72,108,180,192,240,270,312,420,432,462,600,660, %T A162864 810,882,1092,1152,1290,1296,1302,1320,1620,1722,1872,2028,2112,2268, %U A162864 2310,2340,2592,2688,2700,2790,2970,3000,3120,3258,3300,3360,3390,3528,3540 %N A162864 Integers n, divisible by six, for which t = (4^n - 5 * 2^n - 4 * 4^(n^2 - 2n) + 8 * 2^(n^2 - 2n)) / (4 * (n^3 - n)) is an integer %C A162864 Then n - 1 and n + 1 are almost always a pair of twin primes, and the set of these should be an infinite subset of all twin primes. %C A162864 If n - 1 and n + 1 are simultaneously composite, this occurs very rarely. %H A162864 Harvey P. Dale, Table of n, a(n) for n = 1..100 %t A162864 Select[6*Range[600],IntegerQ[(4^#-5*2^#-4*4^(#^2-2#)+8*2^(#^2-2#))/(4*(#^3-#))]&] (* _Harvey P. Dale_, Dec 31 2024 *) %Y A162864 Cf. A001097 %Y A162864 Cf. A001359, A014574, A006512 %K A162864 easy,nonn %O A162864 1,1 %A A162864 _Reikku Kulon_, Jul 15 2009 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE