This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A087594 #7 Dec 05 2013 19:56:32 %S A087594 13,29,31,41,47,53,61,79,83,97,103,113,163,227,229,331,347,367,401, %T A087594 449,487,503,521,523,541,547,557,563,569,587,601,661,709,743,769,821, %U A087594 823,881,883,907,941,947,967,997,1063,1069,1103,1163,1481,1609,1621,1663 %N A087594 Define dd(n) = the number formed by concatenating the absolute difference of successive digits. Sequence contains primes p such that dd(p)=q is a prime, dd(q) is also a prime = r and so on until a single-digit prime (2,3,5,7) arises. (Primes in which the number formed by successive digit differences are primes at every step until a single-digit prime is obtained.). %C A087594 Conjecture: Sequence is infinite. Subsidiary sequence: number of n-digit members. %H A087594 Harvey P. Dale, <a href="/A087594/b087594.txt">Table of n, a(n) for n = 0..1000</a> %e A087594 29 is a member as absolute(2-9) = 7 is a prime. %e A087594 347 is a member as dd(347) = 13, dd(13) = 2. %t A087594 adsd[n_]:=FromDigits[Abs/@Differences[IntegerDigits[n]]]; Select[Prime[ Range[ 300]], And@@PrimeQ[NestWhileList[adsd,adsd[#],IntegerLength[#]>1&]]&] (* _Harvey P. Dale_, Mar 16 2013 *) %Y A087594 Cf. A087593, A087595. %K A087594 base,nonn %O A087594 0,1 %A A087594 _Amarnath Murthy_, Sep 18 2003 %E A087594 More terms from _David Wasserman_, Jun 15 2005