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%I #20 Jan 15 2023 18:37:45
%S 8,18,28,68,78,98,268,318,418,428,498,518,578,598,618,628,668,678,978,
%T 1268,1498,1578,1598,1978,2318,2428,2598,2678,3428,3598,3628,3678,
%U 4318,4418,4498,4978,5518,5618,5678,6268,6428,6618,6628,6668,6978,7498,7598
%N Left truncatable 3-almost primes, in which repeatedly deleting the leftmost digit gives a 3-almost prime at every step until a single-digit 3-almost prime remains.
%C Terms cannot contain any zero digit. - _Harvey P. Dale_, Dec 28 2011
%H Harvey P. Dale, <a href="/A085248/b085248.txt">Table of n, a(n) for n = 1..600</a>
%H I. O. Angell and H. J. Godwin, <a href="http://dx.doi.org/10.1090/S0025-5718-1977-0427213-2">On Truncatable Primes</a>, Math. Comput. 31, 265-267, 1977.
%H <a href="/index/Tri#tprime">Index entries for sequences related to truncatable primes</a>
%e a(7)=268 is a term because 268, 68 and 8 are all 3-almost primes.
%t lt3pQ[n_]:=Module[{idn=IntegerDigits[n]},FreeQ[idn,0]&&Union[ PrimeOmega/@ (FromDigits/@Table[Take[idn,-i],{i,Length[idn]}])] =={3}]; Select[Range[8000],lt3pQ] (* _Harvey P. Dale_, Dec 28 2011 *)
%K nonn,base
%O 1,1
%A _Shyam Sunder Gupta_, Aug 11 2003
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