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 A383810 #13 May 22 2025 00:56:51
%S A383810 373,1913,3733,6737,7937,11353,13997,19937,19997,23773,24113,29347,
%T A383810 31181,31193,31907,34729,37277,38237,41593,47293,59929,71971,72719,
%U A383810 73823,74177,79337,79613,82373,83773,83911,88397,100913,103997
%N A383810 Primes which satisfy the requirements of A380943 in more than one way.
%C A383810 The requirements of A380943 are that primes, written in decimal representation by the concatenation of primes p and q such that the concatenation of q and p also forms a prime.
%C A383810 The number of terms <= 10^k beginning with k=1: 0, 0, 1, 5, 31, 285, 930, 5625, 28137, 205416, ....
%e A383810 373 is a member since 373 is the 74th prime, p=3 and q=73, and the reverse concatenation is 733 which is the 130th prime. In another way, p=37 and q=3 and the reverse concatenation is 337, the 68th prime.
%t A383810 f[n_] := Block[{cnt = 0, id = IntegerDigits@ n, k = 1, len, p, q, qp}, len = Length@ id; While[k < len, p = Take[id, k]; q = Take[id, -len + k]; qp = FromDigits[ Join[q, p]]; If[ PrimeQ[FromDigits[p]] && PrimeQ[FromDigits[q]] && PrimeQ[qp] && IntegerLength[qp] == len, cnt++]; k++]; cnt]; Select[ Prime@ Range@ 10000, f@# > 1 &]
%Y A383810 Cf. A000040, A380943, A383811, A383812, A383813, A383814, A383815, A383816.
%K A383810 base,nonn
%O A383810 1,1
%A A383810 _James C. McMahon_ and _Robert G. Wilson v_, May 11 2025