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A281903 Numbers k such that 6*10^k + 37 is prime. 0
0, 1, 3, 4, 10, 16, 18, 19, 33, 54, 75, 95, 268, 407, 539, 547, 661, 1445, 1559, 2634, 3316, 7047, 10299, 10911, 19528, 29603, 38668 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

For k>1, numbers such that the digit 6 followed by k-2 occurrences of the digit 0 followed by the digits 37 is prime (see Example section).

a(28) > 2*10^5.

LINKS

Table of n, a(n) for n=1..27.

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

Makoto Kamada, Search for 60w37.

EXAMPLE

3 is in this sequence because 6*10^3 + 37 = 6037 is prime.

Initial terms and primes associated:

a(1) = 0, 43;

a(2) = 1, 97;

a(3) = 3, 6037;

a(4) = 4, 60037;

a(5) = 10, 60000000037; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[6*10^# + 37] &]

PROG

(PARI) isok(k) = isprime(6*10^k + 37); \\ Michel Marcus, Dec 10 2018

CROSSREFS

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

Sequence in context: A188022 A007007 A037952 * A093512 A081160 A051437

Adjacent sequences:  A281900 A281901 A281902 * A281904 A281905 A281906

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Feb 01 2017

STATUS

approved

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Last modified May 25 16:40 EDT 2020. Contains 334595 sequences. (Running on oeis4.)