A052078 Smallest prime formed by concatenating n consecutive decreasing numbers, 0 if no such prime exists.

2, 43, 0, 10987, 76543, 0, 73727170696867, 4645444342414039, 0, 56555453525150494847, 219218217216215214213212211210209, 0, 25242322212019181716151413, 6059585756555453525150494847, 0

Offset: 1

Author

Patrick De Geest, Jan 15 2000

Keywords

• nonn
• base
• nice

Comments

Starting numbers in concatenations are given by A052080.

If n is divisible by 3, a(n)=0. - Harvey P. Dale, Jun 03 2019

Links

• C. Rivera, Prime Puzzle 78

Crossrefs

Cf. A052077, A052079, A052080.

Programs

Mathematica

Table[Min[Select[FromDigits[Flatten[IntegerDigits[#]]]&/@ Partition[ Range[ 1000,1,-1],n,1],PrimeQ]],{n,20}]/.\[Infinity]->0 (* Harvey P. Dale, Jun 03 2019 *)

Extensions

Terms for n>6 calculated by Carlos Rivera and Felice Russo