A290751 - OEIS

%I #11 Jul 09 2025 04:44:53

%S 5,11,19,23,29,41,43,59,61,83,101,137,139,149,157,167,191,199,211,227,

%T 241,257,263,271,293,313,317,337,347,349,379,383,389,397,401,457,461,

%U 509,541,563,569,577,631,641,643,661,673,691,727,739,751,757,761,769

%N Primes p such that the concatenation 1p is a semiprime.

%H Alois P. Heinz, <a href="/A290751/b290751.txt">Table of n, a(n) for n = 1..10000</a>

%Y Cf. A290752, A290753.

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Aug 17 2017, following a suggestion from _J. M. Bergot_

%E More terms from _Alois P. Heinz_, Aug 27 2017