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

1,2

Comments

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

Links

Table of n, a(n) for n=1..8.

Crossrefs

Cf. A098129.

Sequence in context: A096834 A013547 A181002 * A099687 A358873 A133651

Adjacent sequences: A323423 A323424 A323425 * A323427 A323428 A323429

Keyword

nonn,easy,base,less

Author

Eder Vanzei, Aug 30 2019

Status

approved