A363353 - OEIS

%I #16 Aug 24 2023 10:15:48

%S 3,4,7,8,10,15,16,21,27,30,37,42,43,54,66,77,96,114,130,132,155,156,

%T 168,182,213,294

%N Numbers k such that 10^k + 3 is a semiprime.

%C a(27) >= 306. - _Amiram Eldar_, Aug 17 2023

%e a(3) = 7 is a term because 10^7 + 3 = 13 * 769231 is a semiprime.

%p select(t -> numtheory:-bigomega(10^t+3) = 2, [$1..70]);

%Y Cf. A001358, A049054, A363352.

%K nonn,more

%O 1,1

%A _Robert Israel_, Aug 16 2023

%E a(18)-a(26) from _Amiram Eldar_, Aug 17 2023