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%I #16 Nov 22 2018 11:20:36
%S 141,142,143,145,146,161,166,169,194,247,249,262,265,267,291,295,298,
%T 299,341,346,361,362,365,391,393,394,395,398,445,446,447,466,469,493,
%U 497,542,543,545,562,565,566,591,597,649,662,667,669,694,695,697,698,699
%N Semiprimes which remain semiprimes when the leftmost and rightmost digits are removed.
%e 169 = 13^2 is in the sequence because 6 = 2*3.
%t Select[Range[100,700],PrimeOmega[#]==PrimeOmega[FromDigits[ Rest[ Most[ IntegerDigits[ #]]]]] ==2&] (* _Harvey P. Dale_, Nov 22 2018 *)
%o (PARI)
%o list(lim)=my(v=List(), t); forprime(p=2, sqrt(lim), t=p; forprime(q=p, lim\t, listput(v, t*q))); vecsort(Vec(v)) \\ From A001358
%o delleft(a) = my(b, c); b=#Str(a); c=a\(10^(b-1)); a-c*(10^(b-1))
%o issemiprime(n) = n>0 && bigomega(n)==2
%o t=list(700); for(n=1, #t, if(issemiprime(delleft(t[n]\10)), print1(t[n],", ")))
%Y Cf. A235687, A235688.
%Y Cf. A227919, A227916, A069686.
%K nonn,base
%O 1,1
%A _Colin Barker_, Jan 14 2014
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