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 A052078 #15 Jun 03 2019 21:21:17
%S A052078 2,43,0,10987,76543,0,73727170696867,4645444342414039,0,
%T A052078 56555453525150494847,219218217216215214213212211210209,0,
%U A052078 25242322212019181716151413,6059585756555453525150494847,0
%N A052078 Smallest prime formed by concatenating n consecutive decreasing numbers, 0 if no such prime exists.
%C A052078 Starting numbers in concatenations are given by A052080.
%C A052078 If n is divisible by 3, a(n)=0. - _Harvey P. Dale_, Jun 03 2019
%H A052078 C. Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_078.htm">Prime Puzzle 78</a>
%t A052078 Table[Min[Select[FromDigits[Flatten[IntegerDigits[#]]]&/@ Partition[ Range[ 1000,1,-1],n,1],PrimeQ]],{n,20}]/.\[Infinity]->0 (* _Harvey P. Dale_, Jun 03 2019 *)
%Y A052078 Cf. A052077, A052079, A052080.
%K A052078 nonn,base,nice
%O A052078 1,1
%A A052078 _Patrick De Geest_, Jan 15 2000
%E A052078 Terms for n>6 calculated by _Carlos Rivera_ and _Felice Russo_