A345528 a(n) is the first prime that begins a sequence of exactly n consecutive primes that are emirps.
97, 13, 71, 733, 3371, 10039, 11897, 334759, 7904639, 1193, 1477271183, 9387802769, 15423094826093
Offset: 1
Examples
a(3) = 71 because the 3 consecutive primes 71, 73, 79 are emirps while the previous and next primes 67 and 83 are not emirps.
Programs
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Maple
digrev:= proc(n) local L,i; L:= convert(n,base,10); add(L[-i]*10^(i-1),i=1..nops(L)) end proc: isemirp:= proc(n) local r; r:= digrev(n); r <> n and isprime(r) end proc: V:= Vector(10): count:= 0: p:= 2: ep:= 0: q:= 2: while count < 10 do p:= nextprime(p); flag:= isemirp(p); if flag then if ep = 0 then q:= p fi; ep:= ep+1; else if ep > 0 then if ep <= 10 and V[ep] = 0 then count:= count+1; V[ep]:= q; fi; fi; ep:= 0; fi od: convert(V,list);
Extensions
a(11)-a(12) from Daniel Suteu, Jun 21 2021
a(13) from Martin Ehrenstein, Jun 28 2021
Comments