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

1,1

Links

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

Mathematica

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

Prog

(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

Crossrefs

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

Sequence in context: A264135 A264020 A020472 * A093948 A116254 A086695

Adjacent sequences: A263428 A263429 A263430 * A263432 A263433 A263434

Keyword

nonn,base,easy

Author

Felix Fröhlich, Oct 18 2015

Status

approved