Search: id:A024770
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%I A024770
%S A024770 2,3,5,7,23,29,31,37,53,59,71,73,79,233,239,293,311,313,317,373,379,593,
%T A024770 599,719,733,739,797,2333,2339,2393,2399,2939,3119,3137,3733,3739,3793,
%U A024770 3797,5939,7193,7331,7333,7393,23333,23339,23399,23993,29399,31193,31379
%N A024770 Right-truncatable primes: every prefix is prime.
%C A024770 Primes in which repeatedly deleting the least significant digit gives 
               a prime at every step until a single digit prime remains.
%C A024770 Comment from Alexander R. Povolotsky (pevnev(AT)juno.com), Jan 22 2008: 
               The subsequence which consists of the following "chain" of consecutive 
               right truncatable primes:
%C A024770 73939133, 7393913, 739391, 73939, 7393, 739, 73, (7)
%C A024770 yields the largest sum, compared with other chains formed from subsets 
               of this sequence:
%C A024770 73939133 + 7393913 + 739391 + 73939 + 7393 + 739 + 73 (+ 7) = 82154588
%D A024770 Angell, I. O. and Godwin, H. J. "On Truncatable Primes." Math. Comput. 
               31, 265-267, 1977.
%H A024770 Jens Kruse Andersen, <a href="b024770.txt">Table of n, a(n) for n = 1..83</
               a> (The full list of terms, taken from link below)
%H A024770 Jens Kruse Andersen, <a href="http://users.cybercity.dk/~dsl522332/math/
               right-truncatable.txt">Right-truncatable primes</a>
%H A024770 P. De Geest, <a href="http://www.worldofnumbers.com/truncat.htm">The 
               list of 4260 left-truncatable primes</a>
%H A024770 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               TruncatablePrime.html">Link to a section of The World of Mathematics.</
               a>
%H A024770 <a href="Sindx_Tri.html#tprime">Index entries for sequences related to 
               truncatable primes</a>
%o A024770 (PARI) {fileO="b024770.txt";v=vector(100);v[1]=2;v[2]=3;v[3]=5;v[4]=7;
               j=4;j1=1; write(fileO,"1 2");write(fileO,"2 3");write(fileO,"3 5");
               write(fileO,"4 7"); until(0,if(j1>j,break);new=1;for(i=j1,j,if(new,
               j1=j+1;new=0);for(k=1,9, z=10*v[i]+k;if(isprime(z),j++;v[j]=z;write(fileO,
               j," ",z);))));} [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Sep 20 2008]
%Y A024770 Cf. A033664, A024785 (left-trucatable primes), A032437, A020994, A052023, 
               A052024, A052025, A050986, A050987.
%Y A024770 Cf. A069866.
%Y A024770 Sequence in context: A124673 A024776 A069867 this_sequence A038603 A106116 
               A091727
%Y A024770 Adjacent sequences: A024767 A024768 A024769 this_sequence A024771 A024772 
               A024773
%K A024770 nonn,base,fini,nice
%O A024770 1,1
%A A024770 David W. Wilson (davidwwilson(AT)comcast.net)
%E A024770 Ends at a(83) = 73939133

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