A263431 Near-repdigit primes with only digits 9 and a single 8 in decimal expansion.

89, 8999, 98999, 99989, 989999, 9899999, 89999999, 99899999, 99998999, 99999989, 998999999, 98999999999, 99989999999, 999998999999, 999999999899, 999999999989, 99899999999999, 99999899999999, 99999999899999, 999999899999999, 999999999989999, 999999999999989

Offset: 1

Author

Felix Fröhlich, Oct 18 2015

Keywords

• nonn
• base
• easy

Links

• Felix Fröhlich, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A020472, A065074, A069661, A105975, A178007.

Programs

Mathematica

Select[Flatten[Table[FromDigits/@Permutations[PadRight[{8},n,9]],{n,15}]],PrimeQ] (* Harvey P. Dale, Mar 29 2020 *)

PARI

a002283(n) = 10^n-1
a011557(n) = 10^n
num(n, k) = a002283(n)-a011557(k)
terms(n) = i=0; x=1; while(x > 0, y=x-1; while(y >= 0, if(ispseudoprime(num(x, y)), print1(num(x, y), ", "); i++); if(i==n, break({2})); y--); x++)
terms(30) \\ print initial thirty terms