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 A226108 Primes remaining prime if all but two digits are deleted 1
 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 113, 131, 137, 173, 179, 197, 311, 317, 431, 617, 719, 1117, 1171, 4111, 11113, 11117, 11119, 11131, 11171, 11173, 11197, 11311, 11317, 11719, 11731, 13171, 13711, 41113 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Subsequence of A069488. REFERENCES C. Caldwell, Truncatable primes, J. Recreational Math., 19:1 (1987) 30-33. LINKS Tim Cieplowski, Table of n, a(n) for n = 1..2720 P. Ballew, Knockout Primes and a new notation, May 17, 2013 C. Caldwell, The Prime Glossary: Deletable Prime EXAMPLE For a(3)=137, all pairs of two digits (in their original order) 13, 17, and 37 are prime. MATHEMATICA testQ[n_] := n > 9 && Catch[Block[{d = IntegerDigits@n}, Do[If[! PrimeQ[ d[[j]] + 10*d[[i]]], Throw@False], {j, 2, Length@d}, {i, j-1}]; True]]; Select[Prime@ Range[10^5], testQ] (* Giovanni Resta, May 28 2013 *) CROSSREFS Cf. A019546, A051362, A069488. Sequence in context: A008364 A140461 A120533 * A273906 A095862 A125845 Adjacent sequences:  A226105 A226106 A226107 * A226109 A226110 A226111 KEYWORD nonn,base AUTHOR Tim Cieplowski, May 26 2013 STATUS approved

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Last modified January 22 07:31 EST 2022. Contains 350481 sequences. (Running on oeis4.)