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A308711
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Left-truncatable primes in base-10 bijective numeration.
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1
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2, 3, 5, 7, 13, 17, 23, 37, 43, 47, 53, 67, 73, 83, 97, 103, 107, 113, 137, 167, 173, 197, 223, 283, 307, 313, 317, 337, 347, 353, 367, 373, 383, 397, 443, 467, 503, 523, 547, 607, 613, 617, 643, 647, 653, 673
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Not identical to A033664; in fact a strict subsequence of A033664. For example, 2003 belongs to A033664 but not to this sequence, since in bijective numerals 2003 is 19X3, whose suffix 9X3 = 1003 = 17 * 59.
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LINKS
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PROG
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(Sage)
DIGITS = "123456789X"
DECODE = {d: i + 1 for i, d in enumerate(DIGITS)}
def decode(s):
return reduce(lambda n, c: 10 * n + DECODE[c], s, 0)
def search(s):
n = decode(s)
if n > 0:
if not is_prime(n): return
yield n
for digit in DIGITS: yield from search(digit + s)
full = sorted(search(""))
full[:10]
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CROSSREFS
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KEYWORD
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nonn,base,easy,fini,full
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AUTHOR
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STATUS
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approved
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