A105107 Numbers n such that 10000n + 1001 is prime.

2, 5, 6, 8, 12, 18, 23, 36, 38, 41, 48, 50, 51, 54, 57, 68, 69, 71, 74, 75, 80, 86, 87, 89, 92, 95, 101, 102, 116, 120, 123, 129, 131, 137, 144, 146, 149, 155, 159, 183, 186, 204, 215, 216, 219, 225, 227, 228, 239, 246, 249, 251, 254, 257, 261, 269, 278, 282

Offset: 1

Author

Parthasarathy Nambi, Apr 07 2005

Keywords

• nonn
• easy

Examples

			n=2: 21001 is prime.
n=69: 691001 is prime.
		

Links

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

Programs

Magma

[ n: n in [1..300] | IsPrime(Seqint([1, 0, 0, 1] cat Intseq(n))) ];

PARI

is(n)=isprime(10000*n+1001) \\ Charles R Greathouse IV, Jun 06 2017

Formula

a(n) ~ 0.4n log n.