%I #11 Jul 23 2024 20:41:40
%S 10,21,33,4,51,6,74,82,9,10,111,121,133,14,15,161,177,183,194,201,21,
%T 22,235,247,25,26,274,287,291,301,314,321,33,34,35,361,371,38,39,403,
%U 411,422,437,445,451,46,471,481,49,501,51,526,533,542,55,562,57,58,591,6001,611,62,633,649,65,662
%N a(n) is the least semiprime that starts with n.
%H Robert Israel, <a href="/A374899/b374899.txt">Table of n, a(n) for n = 1..10000</a>
%e a(5) = 51 because 51 = 3 * 17 is a semiprime that starts with 5, and is the least such semiprime.
%p f:= proc(n) local d,x;
%p if numtheory:-bigomega(n)=2 then return n fi;
%p for d from 1 do
%p for x from n*10^d to (n+1)*10^d-1 do
%p if numtheory:-bigomega(x)=2 then return x fi
%p od od
%p end proc:
%p map(f, [$1..100]);
%Y Cf. A001358, A018800, A374897.
%K nonn,base,look
%O 1,1
%A _Robert Israel_, Jul 22 2024