A034820 Concatenations C1 and C2 and C3 and C4 are all prime (see the comment lines).

16776, 41719, 164612, 188435, 188682, 312184, 317594, 392771, 397617, 450413, 476055, 486283, 492240, 497913, 539471, 584029, 620029, 640883, 648445, 656757, 903009, 992790, 993475, 995917, 1045387, 1082078, 1194606, 1252496, 1322841

Offset: 0

Author

Patrick De Geest, Oct 15 1998

Keywords

• nonn
• base

Comments

C1 = 'prevprime(n) followed by n followed by prevprime(n)'

C2 = 'prevprime(n) followed by n followed by nextprime(n)'

C3 = 'nextprime(n) followed by n followed by prevprime(n)'

C4 = 'nextprime(n) followed by n followed by nextprime(n)'

Examples

			n=41719 -> next prime is 41729, previous prime is 41687, thus '416874171941687' and '416874171941729' and '417294171941687' and '417294171941729' are all four primes.
		

Crossrefs

Cf. A034808-A034821.