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A282358 Numbers k such that (182*10^k + 1)/3 is prime. 0
0, 1, 2, 6, 8, 12, 15, 19, 30, 31, 110, 175, 358, 456, 475, 1359, 1741, 2061, 6062, 7568, 10027, 10732, 27761, 52018, 75456 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

For k>1, numbers such that the digits 60 followed by k-1 occurrences of the digit 6 followed by the digit 7 is prime (see Example section).

a(26) > 10^5.

LINKS

Table of n, a(n) for n=1..25.

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

Makoto Kamada, Search for 606w7.

EXAMPLE

2 is in this sequence because (182*10^2 + 1)/3 = 6067 is prime.

Initial terms and primes associated:

a(1) = 0, 61;

a(2) = 1, 607;

a(3) = 2, 6067;

a(4) = 6, 60666667;

a(5) = 8, 6066666667; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(182*10^# + 1)/3] &]

CROSSREFS

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

Sequence in context: A189515 A190344 A287000 * A064796 A304483 A268177

Adjacent sequences:  A282355 A282356 A282357 * A282359 A282360 A282361

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Feb 13 2017

STATUS

approved

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Last modified November 15 15:59 EST 2018. Contains 317239 sequences. (Running on oeis4.)