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 A051955 #17 Oct 14 2021 18:12:22
%S A051955 4,363,434,484,494,636,4004,46864,47474,135531,695596,1793971,1826281,
%T A051955 1933391,4700074,4785874,4806084,6462646,6574756,9558559,15399351,
%U A051955 46288264,53500535,57499475,150787051,185808581,197636791,226686622
%N A051955 a(n) = smallest palindrome > a(n-1) such that a(1)*a(2)*...*a(n) + 1 and a(1)*a(2)*...*a(n) - 1 are primes.
%t A051955 a[1] = 4; a[n_] := a[n] = For[k = a[n-1]+1, True, k++, id = IntegerDigits[k]; If[id == Reverse[id], p = Product[a[j], {j, 1, n - 1}]*k + 1; If[PrimeQ[p] && PrimeQ[p-2], Return[k]]]]; Table[Print["a(", n, ") = ", a[n]]; a[n], {n, 1, 28}] (* _Jean-François Alcover_, Jul 30 2017 *)
%Y A051955 Cf. A051896, A051954.
%Y A051955 Subsequence of A002113.
%K A051955 nice,nonn,base
%O A051955 1,1
%A A051955 _Felice Russo_, Dec 21 1999
%E A051955 a(12)-a(28) from _Donovan Johnson_, Feb 17 2010