cp's OEIS Frontend

A107812 a(1) = prime(12), for n >= 2, a(n) is the smallest prime not previously used which contains a digit from a(n-1).

%I A107812 #14 Apr 11 2020 10:40:30
%S A107812 37,3,13,11,17,7,47,41,19,29,2,23,31,43,53,5,59,79,67,61,71,73,83,89,
%T A107812 97,107,101,103,109,113,127,131,137,139,149,151,157,163,167,173,179,
%U A107812 181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277
%N A107812 a(1) = prime(12), for n >= 2, a(n) is the smallest prime not previously used which contains a digit from a(n-1).
%C A107812 a(n) = prime(n) for almost all n. Probably a(n) = prime(n) for all n > N for some N, but N must be very large. - _Charles R Greathouse IV_, Jul 20 2011
%F A107812 a(n) ~ n log n. - _Charles R Greathouse IV_, Jul 20 2011
%t A107812 p=Prime[12];b={p};d=p;Do[Do[r=Prime[c];If[FreeQ[b, r]&&Intersection@@IntegerDigits/@{d, r}=!={}, b=Append[b, r];d=r;Break[]], {c, 1000}], {k, 60}];b
%o A107812 (PARI) common(a,b)=a=vecsort(eval(Vec(Str(a))),,8);b=vecsort(eval(Vec(Str(b))),,8);#a+#b>#vecsort(concat(a,b),,8)
%o A107812 in(v,x)=for(i=1,#v,if(v[i]==x,return(1)));0
%o A107812 lista(nn) = {my(v=[37]); for(n=2, nn, forprime(p=2, default(primelimit), if(!in(v,p)&&common(v[#v],p), v=concat(v,p); break))); v; }
%o A107812 \\ _Charles R Greathouse IV_, Jul 20 2011
%Y A107812 Cf. A107353.
%Y A107812 Other cases of seed: A107801 (a(1) = 2), A107802 (a(1) = 3), A107803 (a(1) = 5), A107804 (a(1) = 7), A107805 (a(1) = 11), A107806 (a(1) = 13), A107807 (a(1) = 17), A107808 (a(1) = 19), A107809 (a(1) = 23), A107810 (a(1) = 29), A107811 (a(1) = 31), A107813 (a(1) = 41), A107814 (a(1) = 43).
%K A107812 nonn,base
%O A107812 1,1
%A A107812 _Zak Seidov_ and _Eric Angelini_, May 24 2005