A285937 Numbers k such that 6*10^k + 73 is prime.

0, 2, 3, 5, 6, 14, 15, 38, 60, 66, 95, 101, 206, 225, 1382, 1782, 2046, 2220, 2484, 2592, 4578, 11238, 13016, 18329, 148982, 196070

Offset

1,2

Comments

For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 0 followed by the digits 73 is prime (see Example section).

a(27) > 2*10^5.

Links

Table of n, a(n) for n=1..26.

Makoto Kamada, Factorization of near-repdigit-related numbers.

Makoto Kamada, Search for 60w73.

Example

3 is in this sequence because 6*10^3 + 73 = 6073 is prime.
Initial terms and associated primes:
a(1) = 0, 79;
a(2) = 2, 673;
a(3) = 3, 6073;
a(4) = 5, 600073;
a(5) = 6, 6000073; etc.

Mathematica

Select[Range[0, 100000], PrimeQ[6*10^# + 73] &]

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Sequence in context: A057704 A281382 A078203 * A253647 A131825 A289124

Adjacent sequences: A285934 A285935 A285936 * A285938 A285939 A285940

Keyword

nonn,more,hard

Author

Robert Price, Apr 29 2017

Extensions

a(25)-a(26) from Robert Price, Apr 04 2019

Status

approved