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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
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)'
EXAMPLE
n=41719 -> next prime is 41729, previous prime is 41687, thus '416874171941687' and '416874171941729' and '417294171941687' and '417294171941729' are all four primes.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Oct 15 1998
STATUS
approved