

A296093


Numbers k such that (38*10^k + 349)/9 is prime.


0



0, 2, 3, 8, 27, 30, 39, 141, 387, 626, 972, 1544, 2865, 4371, 5432, 6356, 7545, 9207, 25566, 41313, 41523, 46760, 125166, 187281
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OFFSET

1,2


COMMENTS

For k > 1, numbers such that the digit 4 followed by k2 occurrences of the digit 2 followed by the digits 61 is prime (see Example section).
a(25) > 2*10^5.


LINKS

Table of n, a(n) for n=1..24.
Makoto Kamada, Factorization of nearrepdigitrelated numbers.
Makoto Kamada, Search for 42w61


EXAMPLE

2 is in this sequence because (38*10^2 + 349)/9 = 461 is prime.
Initial terms and primes associated:
a(1) = 0, 43;
a(2) = 2, 461;
a(3) = 3, 4261;
a(4) = 8, 422222261;
a(5) = 27, 4222222222222222222222222261; etc.


MATHEMATICA

Select[Range[0, 100000], PrimeQ[(38*10^# + 349)/9] &]


CROSSREFS

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
Sequence in context: A343438 A107704 A246446 * A041399 A183948 A041503
Adjacent sequences: A296090 A296091 A296092 * A296094 A296095 A296096


KEYWORD

nonn,more,hard


AUTHOR

Robert Price, Dec 04 2017


EXTENSIONS

a(23)a(24) from Robert Price, Oct 01 2018


STATUS

approved



