A102544 Numbers k such that k777777 is prime.

16, 20, 43, 50, 61, 62, 64, 83, 85, 100, 101, 103, 109, 113, 124, 131, 134, 136, 137, 139, 142, 145, 158, 160, 164, 172, 181, 197, 202, 205, 206, 251, 256, 262, 268, 272, 278, 289, 295, 298, 307, 310, 314, 316, 326, 347, 349, 359, 361, 362, 368, 373, 400, 419, 428, 431, 433, 437, 445

Offset: 1

Author

Parthasarathy Nambi, Feb 24 2005

Keywords

• base
• nonn

Examples

			If k=16, then k777777 = 16777777 (prime).
If k=85, then k777777 = 85777777 (prime).
If k=124, then k777777 = 124777777 (prime).
		

Links

• Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Programs

Magma

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

Extensions

More terms from Vincenzo Librandi, Feb 04 2011