A385637 Primes whose decimal expansion consists of the concatenation of m i's followed by m j's, ..., iiijjj, iijj and ij, i != j, where 1 <= i, j <= 9 and m > 0.

13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 44443333444333443343, 55555553333333555555333333555553333355553333555333553353

Offset

1,1

Comments

Similar to A385481, but the blocks of i's and j's are concatenated from longest length to shortest, where a(n) contains terms of a length not recorded in A385481, such as length 56, 182 and 272.

Next term, a(23) has 182 digits and starts with 13 2's followed by 13 9's.

a(24) has 272 digits and starts with 16 9's followed by 16 7's.

a(25), if it exists, has m > 200 and > 40200 digits.

Links

Gonzalo Martínez, Table of n, a(n) for n = 1..24

Example

For i = 4, j = 3 and m = 4, by concatenating 44443333, 444333, 4433 and 43 the prime 44443333444333443343 is obtained.

Crossrefs

Cf. A385481, A059170, A034845.

Sequence in context: A034845 A241059 A385481 * A040136 A049482 A099651

Adjacent sequences: A385634 A385635 A385636 * A385638 A385639 A385640

Keyword

nonn,base

Author

Gonzalo Martínez, Jul 05 2025

Status

approved