A034810 Concatenation of 'prevprime(k) and k and nextprime(k)' is a prime.

7, 10, 13, 16, 19, 36, 37, 40, 43, 46, 58, 63, 74, 85, 88, 97, 98, 104, 125, 132, 143, 153, 156, 164, 168, 169, 175, 188, 196, 203, 206, 222, 224, 233, 241, 269, 292, 304, 305, 308, 311, 317, 331, 333, 338, 344, 359, 364, 367, 368, 372, 382, 389, 395, 397, 409

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

Cf. A034808-A034821.

Sequence in context: A184106 A112414 A329387 * A154487 A023390 A096678

Adjacent sequences: A034807 A034808 A034809 * A034811 A034812 A034813

Keyword

nonn,base

Author

Patrick De Geest, Oct 15 1998

Extensions

Offset changed by Andrew Howroyd, Aug 13 2024

Status

approved