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

0,1

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)'

Links

Table of n, a(n) for n=0..28.

Example

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.

Sequence in context: A052190 A068784 A183844 * A053074 A115923 A243836

Adjacent sequences: A034817 A034818 A034819 * A034821 A034822 A034823

Keyword

nonn,base

Author

Patrick De Geest, Oct 15 1998

Status

approved