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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A290282 Numbers k such that (32*10^k + 337)/9 is prime. 0

%I

%S 0,1,3,4,127,144,213,219,228,463,646,846,1308,1402,1419,1594,1806,

%T 3442,4798,9616,10471,11916

%N Numbers k such that (32*10^k + 337)/9 is prime.

%C For k>1, numbers such that the digit 3 followed by k-2 occurrences of the digit 5 followed by the digits 93 is prime (see Example section).

%C a(23) > 2*10^5.

%H Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>.

%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/primedifficulty.txt">Search for 35w93.</a>

%e 3 is in this sequence because (32*10^3 + 337)/9 = 3593 is prime.

%e Initial terms and primes associated:

%e a(1) = 0, 41;

%e a(2) = 1, 73;

%e a(3) = 3, 3593;

%e a(4) = 4; 35593; etc.

%t Select[Range[0, 100000], PrimeQ[(32*10^# + 337)/9] &]

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

%K nonn,more,hard

%O 1,3

%A _Robert Price_, Jul 25 2017

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 April 19 08:44 EDT 2019. Contains 322241 sequences. (Running on oeis4.)