%I
%S 3,4,5,6,9,10,11,16,20,21,31,39,45,46,54,55,56,60,65,66,86,94,101,115,
%T 126,131,141,145,149,154,155,159,160,164,181,196,219,220,231,241,259,
%U 264,265,306,331,350,351,361,374,386,396,419,420,449,450,456,474,475
%N Numbers k such that both k*(k+1)  1 and k*(k1)  1 are primes.
%H Daniel Starodubtsev, <a href="/A081944/b081944.txt">Table of n, a(n) for n = 1..10000</a>
%e 10 belongs to this sequence as both 9*10  1 = 89 and 10* 11  1 = 109 are primes.
%o (PARI) isok(k) = isprime(k^2+k1) && isprime(k^2k1); \\ _Michel Marcus_, Nov 19 2019
%Y Cf. A081945.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Apr 02 2003
%E More terms from _Don Reble_, Apr 08 2003
