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A034820 Concatenations C1 and C2 and C3 and C4 are all prime (see the comment lines). 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 1 17:49 EST 2022. Contains 358475 sequences. (Running on oeis4.)