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A108822 Primes such that the outer 2 digits are n and n+1 and all inner digits are 5, where 0 < n < 9. 0
859, 65557, 855555559, 6555555557, 855555555555555559, 85555555555555555559, 6555555555555555555557, 85555555555555555555555559, 85555555555555555555555555555555555555559, 6555555555555555555555555555555555555555555555557 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(x) = 10^(x+1)*n+floor(10^x*5/9)*10+n+1. Output if a(x) is prime.
MATHEMATICA
Select[Sort[Flatten[Table[FromDigits[Join[{n}, PadRight[{}, i, 5], {n+1}]], {n, {2, 6, 8}}, {i, 50}]]], PrimeQ] (* Harvey P. Dale, Aug 02 2015 *)
PROG
(PARI) n10np1(n) = { local(x, y, k); for(x=1, n, for(k=1, 8, y=10^(x+1)*k+floor(10^x*5/9)*10+k+1; if(isprime(y), print1(y", ")) ) ) }
CROSSREFS
Sequence in context: A345801 A183628 A187281 * A278156 A249461 A292626
KEYWORD
easy,nonn,base
AUTHOR
Cino Hilliard, Jul 11 2005
EXTENSIONS
One more term (a(10)) from Harvey P. Dale, Aug 02 2015
STATUS
approved

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Last modified March 28 15:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)