

A270890


Numbers k such that (8*10^k + 49)/3 is prime.


497



0, 1, 2, 3, 4, 5, 6, 10, 24, 33, 34, 35, 45, 52, 56, 62, 65, 103, 166, 424, 886, 1418, 1825, 4895, 5715, 7011, 7810, 9097, 12773, 14746, 20085, 25359, 27967, 46629, 48507, 68722, 74944, 102541, 118960, 157368
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,3


COMMENTS

For k>2, numbers such that the digit 2 followed by k3 occurrences of the digit 6 followed by the digits 83 is prime (see Example section).
a(41) > 2*10^5.


LINKS

Table of n, a(n) for n=1..40.
Makoto Kamada, Search for 26w83.


EXAMPLE

3 is in this sequence because (8*10^3 + 49)/3 = 2683 is prime.
Initial terms and primes associated:
a(1) = 0, 19;
a(2) = 1, 43;
a(3) = 2, 283;
a(4) = 3, 2683;
a(5) = 4, 26683;
a(6) = 5, 266683, etc.


MATHEMATICA

Select[Range[0, 100000], PrimeQ[(8*10^# + 49)/3] &]


PROG

(PARI) is(n)=isprime((8*10^n + 49)/3) \\ Charles R Greathouse IV, Feb 16 2017


CROSSREFS

Cf. A056654, A268448, A269303, A270339, A270613, A270831.
Sequence in context: A271341 A306109 A281513 * A010350 A306581 A269858
Adjacent sequences: A270887 A270888 A270889 * A270891 A270892 A270893


KEYWORD

nonn,more


AUTHOR

Robert Price, Mar 25 2016


EXTENSIONS

a(38)a(40) from Robert Price, May 23 2020


STATUS

approved



