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 A034304 Nonprime; becomes prime if any digit is deleted (zeros not allowed in the number). 5
 22, 25, 27, 32, 33, 35, 52, 55, 57, 72, 75, 77, 111, 117, 119, 171, 371, 411, 413, 417, 437, 471, 473, 611, 671, 711, 713, 731, 1379, 1397, 1673, 1739, 1937, 1991, 2233, 2277, 2571, 2577, 2811, 3113, 3131, 3173, 3311, 3317, 3479, 4199, 4331, 4433, 4439 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS From David A. Corneth, Sep 14 2019: (Start) Terms can't contain digits of the form 0 (mod 3), 1 (mod 3) and 2 (mod 3) as then one can remove a digit to get a multiple of 3. Classifying digits mod 3 could give further restrictions on the frequency of digits per class. For example, let (d0, d1, d2) be the frequency of digits from each residue class mod 3 respectively. Then a term can't be of the form (0, 2, 3) as removing a digit from the class 2 (mod 3) gives a multiple of 3. (End) LINKS David A. Corneth, Table of n, a(n) for n = 1..502 (first 200 terms from T. D. Noe, terms n = 201..299 from R. Zumkeller, terms <= 10^11). MATHEMATICA With[{nn=5000}, Select[Complement[Range[10, nn], Prime[Range[ PrimePi[ nn]]]], DigitCount[#, 10, 0]==0&&And@@PrimeQ[FromDigits/@Subsets[ IntegerDigits[#], {IntegerLength[#]-1}]]&]] (* Harvey P. Dale, Apr 06 2012 *) PROG (Haskell) a034304 n = a034304_list !! (n-1) a034304_list = map read \$ filter (f "") \$                map show \$ dropWhile (< 10) a259315_list :: [Integer] where    f _ "" = True    f us (v:vs) = a010051' (read (us ++ vs)) == 1 && f (us ++ [v]) vs -- Reinhard Zumkeller, Jun 24 2015 CROSSREFS Cf. A034302-A034305. Cf. A010051, A259315. Sequence in context: A177734 A177055 A186780 * A167459 A066737 A121609 Adjacent sequences:  A034301 A034302 A034303 * A034305 A034306 A034307 KEYWORD base,nonn,nice AUTHOR EXTENSIONS Definition corrected by T. D. Noe, Apr 02 2008 STATUS approved

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Last modified October 17 06:08 EDT 2019. Contains 328106 sequences. (Running on oeis4.)