

A294915


Numbers k such that (13*10^k  139)/9 is prime.


0



3, 7, 46, 51, 87, 124, 141, 301, 309, 400, 667, 1749, 2512, 3859, 4323, 4515, 9238, 9592
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OFFSET

1,1


COMMENTS

For k > 1, numbers such that the digit 1 followed by k2 occurrences of the digit 4 followed by the digits 29 is prime (see Example section).
a(18) > 2*10^5.


LINKS



EXAMPLE

3 is in this sequence because (13*10^3  139)/9 = 1429 is prime.
Initial terms and primes associated:
a(1) = 3, 1429;
a(2) = 7, 14444429;
a(3) = 46, 14444444444444444444444444444444444444444444429;
a(4) = 51, 1444444444444444444444444444444444444444444444444429; etc.


MATHEMATICA

Select[Range[2, 100000], PrimeQ[(13*10^#  139)/9] &]


CROSSREFS



KEYWORD

nonn,more,hard


AUTHOR



STATUS

approved



