A290282 Numbers k such that (32*10^k + 337)/9 is prime.

0, 1, 3, 4, 127, 144, 213, 219, 228, 463, 646, 846, 1308, 1402, 1419, 1594, 1806, 3442, 4798, 9616, 10471, 11916

Offset

1,3

Comments

For k>1, numbers such that the digit 3 followed by k-2 occurrences of the digit 5 followed by the digits 93 is prime (see Example section).

a(23) > 2*10^5.

Links

Table of n, a(n) for n=1..22.

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

Makoto Kamada, Search for 35w93.

Example

3 is in this sequence because (32*10^3 + 337)/9 = 3593 is prime.
Initial terms and primes associated:
a(1) = 0, 41;
a(2) = 1, 73;
a(3) = 3, 3593;
a(4) = 4; 35593; etc.

Mathematica

Select[Range[0, 100000], PrimeQ[(32*10^# + 337)/9] &]

Crossrefs

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

Sequence in context: A308944 A280735 A356073 * A331815 A077032 A370385

Adjacent sequences: A290279 A290280 A290281 * A290283 A290284 A290285

Keyword

nonn,more,hard

Author

Robert Price, Jul 25 2017

Status

approved