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

1,1

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.

Links

Giovanni Resta, Table of n, a(n) for n = 1..33 (terms < 10^36)

Carlos Rivera, Puzzle 786

Example

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

Mathematica

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

Crossrefs

Cf. A258183, A258184.

Sequence in context: A065786 A015463 A177507 * A048605 A165210 A162454

Adjacent sequences: A258179 A258180 A258181 * A258183 A258184 A258185

Keyword

nonn,base

Author

Giovanni Resta, May 23 2015

Status

approved