

A280060


Numbers k such that (2*10^k + 49)/3 is prime.


0



0, 1, 2, 3, 5, 6, 7, 8, 13, 21, 22, 25, 26, 38, 200, 395, 442, 561, 908, 1295, 5541, 7795, 8600, 19157, 22536, 45636
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OFFSET

1,3


COMMENTS

For k>1, numbers such that k2 occurrences of the digit 6 followed by the digits 83 is prime (see Example section).
a(27) > 2*10^5.


LINKS



EXAMPLE

3 is in this sequence because (2*10^3 + 49) / 3 = 683 is prime.
Initial terms and primes associated:
a(1) = 0, 17;
a(2) = 1, 23;
a(3) = 2, 83;
a(4) = 3, 683;
a(5) = 5, 66683; etc.


MATHEMATICA

Select[Range[0, 100000], PrimeQ[(2*10^# + 49) / 3] &]


PROG



CROSSREFS



KEYWORD

nonn,more,hard


AUTHOR



STATUS

approved



