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Search: id:A108794
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| A108794 |
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Primes whose 10's complement is a semiprime, i.e. p is prime and 10^L - p is a semiprime, where L is the number of digits in p. |
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+0
1
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| 13, 23, 31, 43, 61, 67, 79, 101, 107, 131, 149, 151, 157, 193, 197, 211, 229, 233, 251, 263, 269, 277, 283, 293, 311, 313, 331, 367, 389, 409, 419, 421, 449, 457, 463, 467, 499, 503, 547, 563, 587, 593, 607, 619, 659, 661, 673, 677, 691, 701, 709, 733, 751
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Some twin prime terms are (149,151), (311,313), (419,421), (659,661), ... Conjecture: there are infinitely many twin primes in this sequence.
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EXAMPLE
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563 is a term because it is prime and 10^3-563 = 437 = 19*23.
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CROSSREFS
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Sequence in context: A102498 A019399 A061967 this_sequence A089777 A050857 A070219
Adjacent sequences: A108791 A108792 A108793 this_sequence A108795 A108796 A108797
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KEYWORD
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easy,nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Jul 09 2005
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