OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
n=353 -> next prime is 359, previous prime is 349, thus '359353349' is a prime.
MATHEMATICA
Select[Range[500], PrimeQ[FromDigits[Flatten[IntegerDigits/@ { NextPrime[#], #, NextPrime[ #, -1]}]]]&] (* Harvey P. Dale, Jan 12 2016 *)
PROG
(PARI) isok(n)=n>2 && isprime(fromdigits(concat([digits(nextprime(n+1)), digits(n), digits(precprime(n-1))]))) \\ Andrew Howroyd, Aug 13 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Oct 15 1998
EXTENSIONS
Offset changed by Andrew Howroyd, Aug 13 2024
STATUS
approved