A034594 Concatenation of nextprime(a(n)) and a(n) is a prime.

3, 27, 33, 39, 47, 51, 53, 61, 63, 91, 111, 123, 129, 131, 143, 173, 189, 199, 211, 217, 219, 231, 233, 237, 257, 273, 279, 301, 319, 341, 353, 357, 417, 423, 429, 473, 481, 489, 493, 501, 519, 523, 529, 531, 537, 551, 561, 573, 579, 587, 597, 607, 609, 619

Offset: 1

Author

Patrick De Geest, Oct 15 1998

Keywords

• nonn
• base

Examples

			a(n)=27 -> nextprime(a(n)) is 29 so '2927' is a prime.
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..10000

Crossrefs

See also A034591-A034596, A030459.

Programs

PARI

isok(n)=isprime(fromdigits(concat(digits(nextprime(n+1)), digits(n)))) \\ Andrew Howroyd, Aug 13 2024

Extensions

Offset changed by Andrew Howroyd, Aug 13 2024