A323426 a(n) = decimal concatenation of n (once), n-1 (twice), n-2 (3 times), ..., 1 (n times).

1, 211, 322111, 4332221111, 544333222211111, 655444333322222111111, 7665554444333332222221111111, 877666555544444333333222222211111111

Offset: 1

Author

Eder Vanzei, Aug 30 2019

Keywords

• nonn
• easy
• base
• less

Comments

a(2), a(3) and a(4) are primes.

Crossrefs

Cf. A098129.