A001731 a(n) is 9 written in base 10-n.

9, 10, 11, 12, 13, 14, 21, 100, 1001, 111111111

Offset: 0

Author

N. J. A. Sloane

Keywords

• fini
• nonn
• base
• full

Crossrefs

Cf. A001732, A001733, A001734, A001735, A001736.

Programs

Mathematica

Append[Array[FromDigits@ IntegerDigits[9, 10 - #] &, 9, 0], FromDigits@ ConstantArray[1, 9]] (* Michael De Vlieger, Feb 02 2022 *)

PARI

a(n) = if (n==9, 111111111, fromdigits(digits(9, 10-n), 10)); \\ Michel Marcus, Feb 02 2022

Extensions

Corrected by Henry Bottomley, Nov 23 2000