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Lexicographically earliest sequence of positive integers such that the absolute difference of any two adjacent digits is prime.
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%I #18 Dec 23 2024 14:53:43

%S 1,3,5,2,4,6,8,13,14,7,9,20,24,16,18,30,25,27,29,41,31,35,36,38,50,52,

%T 42,46,47,49,61,63,53,57,58,64,68,69,70,72,74,75,79,202,92,94,96,81,

%U 83,85,86,97,203,130,205,207,241,302,413,131,303,135,242,414,136,138,141,305,246,142,416,146,147,247,249,250

%N Lexicographically earliest sequence of positive integers such that the absolute difference of any two adjacent digits is prime.

%C See A219250 for the version allowing nonnegative integers, i.e., starting with a(1)=0.

%C See A219248 for the numbers which occur in this sequence, and A219251 for the complement.

%H E. Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2013-April/011035.html">Any digit-pair in S sums to a prime</a>, SeqFan list, Apr 11 2013

%o (PARI) {A219249(n,a=[1],u=0)=while(#a<n,u+=1<<a[#a];for(t=a[1]+1,9e9,bittest(u,t)&next;my(d=concat(a[#a]%10,digits(t)));for(i=2,#d,isprime(abs(d[i-1]-d[i]))||next(2));a=concat(a,t);break));a}

%Y Cf. A182175, A182177, A182178.

%K nonn,base

%O 1,2

%A _Eric Angelini_ and _M. F. Hasler_, Apr 11 2013