A102374 Numbers k such that k77777 is prime.

24, 32, 39, 50, 54, 66, 74, 75, 78, 83, 90, 99, 101, 108, 110, 114, 135, 143, 152, 159, 167, 173, 186, 188, 204, 206, 207, 209, 219, 221, 230, 233, 236, 242, 248, 251, 255, 261, 263, 264, 276, 279, 284, 285, 321, 338, 341, 356, 362, 372, 374, 380, 393, 401, 404, 422, 426, 428, 431, 437, 461

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

If k=24, then k77777 = 2477777 (prime).
If k=66, then k77777 = 6677777 (prime).
If k=99, then k77777 = 9977777 (prime).

Mathematica

Select[Range[500], PrimeQ[#*10^5+77777]&] (* Harvey P. Dale, Sep 19 2020 *)

Prog

(Magma) [ n: n in [1..700] | IsPrime(Seqint([7, 7, 7, 7, 7] cat Intseq(n))) ]; // Vincenzo Librandi, Feb 04 2011

Crossrefs

Sequence in context: A289554 A334589 A334936 * A364353 A317534 A240068

Adjacent sequences: A102371 A102372 A102373 * A102375 A102376 A102377

Keyword

base,nonn

Author

Parthasarathy Nambi, Feb 22 2005

Status

approved