A349805 a(n) = A261138(n)/11.

1, 111, 11211, 1122211, 112232211, 11223332211, 1122334332211, 112233444332211, 11223344544332211, 112233444636544332211, 1122334446373736544332211, 11223344463737473736544332211, 112233444637374666473736544332211, 1122334446373746649466473736544332211, 11223344463737466492319466473736544332211

Offset: 1

Author

N. J. A. Sloane, Dec 01 2021

Keywords

• nonn
• base

Crossrefs

Cf. A261138.

A109242 has the same initial terms.

Programs

Maple

a:= n-> (s-> parse(cat(s, seq(s[-i], i=1..length(s))))/11)(cat("", $1..n)):
seq(a(n), n=1..14);  # Alois P. Heinz, Dec 01 2021

Python

def A349805(n): return int((lambda x: x+x[::-1])(''.join(str(d) for d in range(1,n+1))))//11 # Chai Wah Wu, Dec 01 2021

Extensions

More than the usual number of terms are shown in order to distinguish this from several similar sequences.