login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A295522 Numbers k such that (16*10^k + 107)/3 is prime. 0
0, 1, 2, 8, 18, 24, 96, 152, 204, 296, 566, 703, 1814, 4342, 4626, 5412, 6704, 6752, 7096, 27004, 37976, 173251 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

For k > 1, numbers such that the digit 5 followed by k-2 occurrences of the digit 3 followed by the digits 69 is prime (see Example section).

a(23) > 2*10^5.

LINKS

Table of n, a(n) for n=1..22.

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

Makoto Kamada, Search for 53w69

EXAMPLE

2 is in this sequence because (16*10^2 + 107)/3 = 569 is prime.

Initial terms and primes associated:

a(1) = 0, 41;

a(2) = 1, 89;

a(3) = 2, 569;

a(4) = 8, 533333369;

a(5) = 18, 5333333333333333369; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(16*10^# + 107)/3] &]

CROSSREFS

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

Sequence in context: A171613 A306394 A109136 * A065131 A192157 A268810

Adjacent sequences:  A295519 A295520 A295521 * A295523 A295524 A295525

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Nov 28 2017

EXTENSIONS

a(22) from Robert Price, Mar 06 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 24 00:38 EDT 2019. Contains 323528 sequences. (Running on oeis4.)