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%I #9 Jan 25 2017 17:23:18
%S 1,2,4,9,11,12,17,18,21,22,26,28,29,31,34,37,43,49,56,57,64,66,68,79,
%T 86,88,104,106,114,117,119,121,133,138,144,148,152,166,171,172,182,
%U 183,192,193,199,204,207,208,213,218,224,229,232,233,242,244,249,257,264,268,276
%N Numbers n such that 42n - 5 and 42n + 5 are prime.
%H Ivan Neretin, <a href="/A172147/b172147.txt">Table of n, a(n) for n = 1..10000</a>
%e a(1)=1 because 42*1 - 5 = 37 and 42*1 + 5 = 47 are both prime.
%t Select[Range[280], PrimeQ[42 # - 5] && PrimeQ[42 # + 5] &] (* _Ivan Neretin_, Jan 24 2017 *)
%K nonn,easy
%O 1,2
%A _Juri-Stepan Gerasimov_, Jan 26 2010
%E Corrected by _Charles R Greathouse IV_, Mar 19 2010
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