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%I #7 Mar 29 2020 02:19:25
%S 24,25,27,32,34,38,45,49,55,57,62,64,76,77,80,84,85,87,91,92,93,94,
%T 104,110,115,117,118,121,122,123,124,129,132,133,142,143,144,145,147,
%U 152,154,159,160,161,164,169,170,171,175,177,182,184,185,187,188,195,201
%N Numbers k such that k, k+1 and 2*k+1 are composite.
%C Also numbers n such that A098735(n) = 1. Also numbers n such that A098077(n) divides n!. Note that n, n+1 and 2n+1 are all primes only for n = 2.
%H Amiram Eldar, <a href="/A123608/b123608.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[Range[500],!PrimeQ[ # ]&&!PrimeQ[ #+1]&&!PrimeQ[2#+1]&]
%Y Cf. A098735, A098077.
%K nonn
%O 1,1
%A _Alexander Adamchuk_, Nov 15 2006
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