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A274976 Numbers n such that (26*10^n + 31)/3 is prime. 0
0, 1, 2, 3, 4, 7, 9, 57, 98, 122, 123, 249, 304, 318, 339, 374, 390, 476, 619, 1358, 1724, 3351, 5046, 5572, 6685, 9421, 14362, 97353 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

For n>1, numbers n such that the digit 8 followed by n-2 occurrences of the digit 6 followed by the digits 77 is prime (see Example section).

a(29) > 10^5.

LINKS

Table of n, a(n) for n=1..28.

Makoto Kamada, Factorization of near-repdigit-related numbers.

Makoto Kamada, Search for 86w77.

EXAMPLE

3 is in this sequence because (26*10^3 + 31)/3 = 877 is prime.

Initial terms and primes associated:

a(1) = 0, 19;

a(2) = 1, 97;

a(3) = 2, 877;

a(4) = 3, 8677;

a(5) = 4, 86677, etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(26*10^# + 31)/3] &]

CROSSREFS

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

Sequence in context: A071114 A078696 A256772 * A269729 A098115 A182833

Adjacent sequences:  A274973 A274974 A274975 * A274977 A274978 A274979

KEYWORD

nonn,more

AUTHOR

Robert Price, Jul 14 2016

STATUS

approved

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Last modified May 24 03:21 EDT 2017. Contains 286937 sequences.