A275538 Numbers n such that (38*10^n + 547)/9 is prime.

1, 3, 4, 9, 10, 13, 19, 21, 25, 28, 70, 81, 97, 106, 291, 369, 460, 577, 4705, 5427, 7153, 7191, 7885, 12070, 20794, 34855

Offset

1,2

Comments

For n>1, numbers such that the digit 4 followed by n-2 occurrences of the digit 2 followed by the digits 83 is prime (see Example section).

a(27) > 10^5.

Links

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

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

Makoto Kamada, Search for 42w83.

Example

3 is in this sequence because (38*10^3 + 547)/9 = 4283 is prime.
Initial terms and primes associated:
a(1) = 1, 103;
a(2) = 3, 4283;
a(3) = 4, 42283;
a(4) = 9, 4222222283;
a(5) = 10, 42222222283, etc.

Mathematica

Select[Range[0, 100000], PrimeQ[(38*10^# + 547)/9] &]

Prog

(PARI) isok(n) = isprime((38*10^n + 547)/9); \\ Michel Marcus, Aug 01 2016

Crossrefs

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

Sequence in context: A287323 A059985 A137709 * A090120 A129783 A301919

Adjacent sequences: A275535 A275536 A275537 * A275539 A275540 A275541

Keyword

nonn,more

Author

Robert Price, Aug 01 2016

Status

approved