A176089 Numbers n such that 4(10^n-1)/9 * 10^ceiling(log_10(n+1)) + n is prime.

1, 547, 1187, 11183

Offset: 1

Author

Rick L. Shepherd, Apr 11 2010

Keywords

• more
• nonn

Comments

No term is a multiple of 2, 3, or 5. The decimal expansion of each corresponding prime is n 4's with n's decimal expansion concatenated. Probable primes found by PrimeForm. Primes for 547 and 1187 proved by Primo. No more terms up to 30000.

Examples

			The first term is 1 because 41 is prime.
		

Crossrefs

Cf. n k's followed by n is prime: A070746 (k=1), A176087 (k=3), A176090 (k=6), A084428 (k=7), A176091 (k=9). [k=2, 5, and 8 produce only composites divisible by 3.]