1,1

Primes in which repeatedly deleting the least significant digit gives a prime at every step until a single digit prime remains.

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:

73939133, 7393913, 739391, 73939, 7393, 739, 73, (7)

yields the largest sum, compared with other chains formed from subsets of this sequence:

73939133 + 7393913 + 739391 + 73939 + 7393 + 739 + 73 (+ 7) = 82154588

Angell, I. O. and Godwin, H. J. "On Truncatable Primes." Math. Comput. 31, 265-267, 1977.

Jens Kruse Andersen, Table of n, a(n) for n = 1..83 (The full list of terms, taken from link below)

Jens Kruse Andersen, Right-truncatable primes

P. De Geest, The list of 4260 left-truncatable primes

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

Index entries for sequences related to truncatable primes

(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]

Cf. A033664, A024785 (left-trucatable primes), A032437, A020994, A052023, A052024, A052025, A050986, A050987.

Cf. A069866.

Sequence in context: A124673 A024776 A069867 this_sequence A038603 A106116 A091727

Adjacent sequences: A024767 A024768 A024769 this_sequence A024771 A024772 A024773

nonn,base,fini,nice

David W. Wilson (davidwwilson(AT)comcast.net)

Ends at a(83) = 73939133