A089186 Decreases from 9 * 10^k down to 1, restarting at 9 * 10^(k+1).

9, 8, 7, 6, 5, 4, 3, 2, 1, 90, 89, 88, 87, 86, 85, 84, 83, 82, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28

Offset: 1

Author

Artemario Tadeu Medeiros da Silva (artemario(AT)uol.com.br), Dec 07 2003

Keywords

• base
• easy
• nonn

Comments

Points of local maxima: 9 * 10^k.

a(n) is the 10's complement of n. - Robert Israel, Jul 03 2024

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..9999

Crossrefs

Cf. A052268, A178914 (essentially the same).

Programs

Magma

[10^#Intseq(n)-n : n in [1..68]]; // Arkadiusz Wesolowski, Nov 09 2013

Maple

a:= n-> 10^length(n)-n:
seq(a(n), n=1..72);  # Alois P. Heinz, Sep 18 2024

Mathematica

Join[Range[9,1,-1],Range[90,1,-1]] (* Harvey P. Dale, Jun 06 2013 *)

PARI

a(n) = 10^(1+logint(n, 10)) - n \\ Ruud H.G. van Tol, Jan 16 2023

Formula

a(n) = 10^(floor(log_10(n)) + 1) - n.