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 A087596 Largest n-digit member of A087593. Define dd(k) = the number formed by concatenating the absolute difference of successive digits of k. Sequence contains largest n-digit prime p such that dd(p) is also prime. 1
 97, 997, 9967, 99989, 999907, 9999907, 99999989, 999999607, 9999999967, 99999999947, 999999999989, 9999999999701, 99999999999923, 999999999999989, 9999999999999887, 99999999999999997, 999999999999999989 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS Conjecture: Sequence is infinite. LINKS EXAMPLE a(5) = 99989 and dd(99989) = 0011 = 11 is a prime. MATHEMATICA npr[n_]:=Module[{pr=NextPrime[10^n, -1]}, While[!PrimeQ[FromDigits[Abs[ Differences[ IntegerDigits[pr]]]]], pr=NextPrime[pr, -1]]; pr]; Array[ npr, 20, 2] (* Harvey P. Dale, Mar 06 2012 *) CROSSREFS Cf. A087593, A087594, A087595. Sequence in context: A127748 A127828 A186075 * A133836 A224106 A038532 Adjacent sequences:  A087593 A087594 A087595 * A087597 A087598 A087599 KEYWORD base,nonn AUTHOR Amarnath Murthy, Sep 18 2003 EXTENSIONS More terms from David Wasserman, Jun 15 2005 STATUS approved

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Last modified June 25 15:29 EDT 2022. Contains 354851 sequences. (Running on oeis4.)