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 A262552 Numbers n such that the concatenation of the decimal numbers 1 through n, but omitting 5, is a prime. 2
 11, 17, 157, 3631 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The corresponding primes are the primes in A262575. The actual values of a(1) to a(4) are also primes, although that is not a necessary condition for a number to belong to this sequence. Not all the terms of A262300 are primes, for example. Probabilistic arguments suggest the sequence is infinite. a(5) > 10000. - Robert Price, Nov 03 2018 LINKS EXAMPLE The first two terms correspond to the primes 123467891011 and 123467891011121314151617. a(3) corresponds to a 362-digit prime, a(4) to a 13416-digit probable prime. These two terms were found by David Broadhurst on Oct 08 2015. CROSSREFS Cf. A262575, A262300, A007908. Sequence in context: A226677 A056577 A166655 * A279332 A286959 A146446 Adjacent sequences:  A262549 A262550 A262551 * A262553 A262554 A262555 KEYWORD nonn,base,more AUTHOR N. J. A. Sloane, Oct 09 2015 STATUS approved

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Last modified May 17 05:13 EDT 2021. Contains 343965 sequences. (Running on oeis4.)