|
|
A108830
|
|
Primes such that the outer 2 digits are n and n-1 and all inner digits are 2, where 0 < n < 9.
|
|
0
|
|
|
827, 2221, 42223, 4222222223, 42222222223, 222222222222222221, 822222222222222222227, 42222222222222222222222222222223, 8222222222222222222222222222222227, 822222222222222222222222222222222222222222222222222222222222227
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
Sort[Select[Flatten[Table[FromDigits[Join[{n}, PadRight[{}, i, 2], {n-1}]], {n, 2, 8, 2}, {i, 70}]], PrimeQ]] (* Harvey P. Dale, Dec 05 2015 *)
|
|
PROG
|
(PARI) n10np1(n, d) = { local(x, y, k); for(x=1, n, for(k=1, 8, y=10^(x+1)*k+floor(10^x*d/9)*10+k-1; if(isprime(y), print1(y", ")) ) ) }
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn,base
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|