A365598 Near-repdigit primes with at least two 9's as the repeated digit, and ending in a distinct digit.

991, 997, 99991, 9999991, 99999999999999997, 999999999999999999999999999999991, 999999999999999999999999999999999999999999991

Offset: 1

Author

Robert Price, Sep 10 2023

Keywords

• base
• nonn

Comments

The usual definition of near-repdigit prime allows the distinct digit to be in any position, see A105975 for that (super) sequence.

Examples

			99991 is a term because all digits are equal to 9 except the last one.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..15 (first 14 terms from Robert Price)

Crossrefs

Subsequence of A105975.

Cf. A105976, A105978, A105979, A105980, A105982, A365592, A365596, A365597.

Programs

Maple

R:= NULL: count:= 0:
for n from 3 to 999 do
  for d in [9,3] do
    if isprime(10^n - d) then
      R:= R, 10^n-d; count:= count+1;
    fi
od od:
R;

Extensions

Definition corrected by M. F. Hasler, Jun 20 2025