OFFSET
1,1
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..10000
EXAMPLE
n=88 --> previous prime is 83, next prime is 89, thus '838889' is a prime.
MATHEMATICA
coQ[n_]:=PrimeQ[FromDigits[Flatten[IntegerDigits[{NextPrime[n, -1], n, NextPrime[n]}]]]]; Select[Range[3, 409], coQ[#]&] (* Jayanta Basu, May 30 2013 *)
PROG
(PARI) isok(n)=n>2 && isprime(fromdigits(concat([digits(precprime(n-1)), digits(n), digits(nextprime(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