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.

97, 997, 9967, 99989, 999907, 9999907, 99999989, 999999607, 9999999967, 99999999947, 999999999989, 9999999999701, 99999999999923, 999999999999989, 9999999999999887, 99999999999999997, 999999999999999989

Offset

2,1

Comments

Conjecture: Sequence is infinite.

Links

Table of n, a(n) for n=2..18.

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