A258182 Numbers which divide the concatenation of the two previous primes.

7, 43, 4167, 857143, 909091, 1443299, 4166667, 92857143, 2205882353, 2792792793, 1046511627907, 5737704918033, 19083969465649, 53947368421053, 55882352941177, 772727272727273, 2962962962962962963, 5806451612903225807, 263888888888888888889

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 43 is in the sequence because the two previous primes are 37 and 41 and 3741 is divisible by 43.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..33 (terms < 10^36)
• Carlos Rivera, Puzzle 786

Crossrefs

Cf. A258183, A258184.

Programs

Mathematica

Select[Range[4,10^6], Divisible[ FromDigits[ Join@@ IntegerDigits@ NextPrime[#, {-2,-1}]], #]&]