A258184 Numbers which divide the concatenation of the next two primes.

1, 3, 7, 61, 167, 801, 1143, 2001, 6001, 8001, 125001, 25000001, 181818181819, 2500000000001, 16666666666667, 45000000000001, 640000000000001, 1142857142857143, 4000000000000001, 37500000000000001, 153846153846153847, 937500000000000001, 2881355932203389831

Offset: 1

Author

Giovanni Resta, May 23 2015

Keywords

• nonn
• base

Comments

The terms greater than 10^18 are obtained assuming that nextprime(n) < n + (log n)^2, which is known to hold at least for 4 < n < 10^18.

Examples

			The number 7 is in the sequence since the next two primes are 11 and 13 and 1113 is divisible by 7.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..40 (terms < 10^36)
• Carlos Rivera, Puzzle 786

Crossrefs

Cf. A258182, A258183.

Programs

Mathematica

Select[Range[10^5], Divisible[ FromDigits[ Join@@ IntegerDigits@ NextPrime[#, {1, 2}]], #]&]