

A271269


Numbers n such that 8*10^n49 is prime.


489



1, 2, 3, 8, 24, 49, 57, 74, 104, 131, 144, 162, 182, 246, 302, 352, 557, 581, 589, 704, 939, 1181, 1937, 2157, 4463, 6013, 7266, 8504, 8691, 16129, 20108, 40677, 74234
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OFFSET

1,2


COMMENTS

For n>1, numbers such that the digit 7 followed by n2 occurrences of the digit 9 followed by the digits 51 is prime (see Example section).
a(34) > 10^5.


LINKS

Table of n, a(n) for n=1..33.
Makoto Kamada, Search for 79w51.


EXAMPLE

3 is in this sequence because 8*10^349 = 7951 is prime.
Initial terms and primes associated:
a(1) = 1, 31;
a(2) = 2, 751;
a(3) = 3, 7951;
a(4) = 8, 799999951;
a(6) = 24, 7999999999999999999999951, etc.


MATHEMATICA

Select[Range[0, 100000], PrimeQ[8*10^#49] &]


PROG

(PARI) is(n)=isprime(8*10^n49) \\ Charles R Greathouse IV, Feb 16 2017


CROSSREFS

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929.
Sequence in context: A301462 A120763 A120708 * A089847 A304121 A038561
Adjacent sequences: A271266 A271267 A271268 * A271270 A271271 A271272


KEYWORD

nonn,more,changed


AUTHOR

Robert Price, Apr 03 2016


STATUS

approved



