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A271377 Numbers k such that (28*10^k - 43)/3 is prime. 0
1, 2, 3, 4, 5, 6, 7, 13, 43, 112, 114, 127, 242, 247, 251, 335, 450, 616, 816, 1237, 1448, 4303, 4865, 5414, 6427, 9045, 10391, 12651, 25071, 27901, 50362, 58843, 67378, 68107 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For k>1, numbers such that the digit 9 followed by k-2 occurrences of the digit 3 followed by the digits 19 is prime (see Example section).

a(35) > 2*10^5.

LINKS

Table of n, a(n) for n=1..34.

Makoto Kamada, Search for 93w19.

EXAMPLE

3 is in this sequence because (28*10^3 - 43)/3 = 9319 is prime.

Initial terms and primes associated:

a(1) = 1, 79;

a(2) = 2, 919;

a(3) = 3, 9319;

a(4) = 4, 93319;

a(5) = 5, 933319, etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(28*10^# - 43)/3] &]

PROG

(PARI) lista(nn) = for(n=1, nn, if(ispseudoprime((28*10^n - 43)/3), print1(n, ", "))); \\ Altug Alkan, Apr 05 2016

CROSSREFS

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

Sequence in context: A032990 A060810 A319723 * A066336 A076133 A277908

Adjacent sequences:  A271374 A271375 A271376 * A271378 A271379 A271380

KEYWORD

nonn,more

AUTHOR

Robert Price, Apr 05 2016

STATUS

approved

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Last modified March 28 15:09 EDT 2020. Contains 333089 sequences. (Running on oeis4.)