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%I #22 Jul 08 2024 16:04:53
%S 5,11,29,41,71,239,419,461,599,1481,1721,2549,2969,3539,4421,8009,
%T 10301,17291,19181,20021,23561,24179,27059,31151,35531,41411,42641,
%U 43889,46439,47741,53591,55931,60761,83231,84389,95789,98909,123551,143261,156419,164429
%N Primes p of the form k*(k + 1) - 1 such that p and p + 2 are twin primes.
%C a(n) + 1 is an oblong number (A002378). - _Michel Marcus_, Feb 04 2017
%H Amiram Eldar, <a href="/A088486/b088486.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A088485(n)*(A088485(n) + 1) - 1. - _R. J. Mathar_, Nov 14 2009
%e 20*20 + 20 - 1 = 419, 419 and 421 twin primes, 419 is the 7th of the sequence for k = 20.
%t Select[Table[k(k+1)-1,{k,500}],AllTrue[#+{0,2},PrimeQ]&] (* _Harvey P. Dale_, Jul 08 2024 *)
%Y Cf. A002378, A088485.
%K nonn,changed
%O 1,1
%A _Pierre CAMI_, Nov 09 2003
%E Sign in definition corrected by _R. J. Mathar_, Nov 13 2009
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