A216156 Period of powers of 11 mod 10^n.

10, 50, 500, 5000, 50000, 500000, 5000000, 50000000, 500000000, 5000000000, 50000000000, 500000000000, 5000000000000, 50000000000000, 500000000000000, 5000000000000000, 50000000000000000, 500000000000000000

Offset: 1

Author

V. Raman, Sep 02 2012

Keywords

• nonn
• base
• easy

Comments

Essentially the same as A093143. - R. J. Mathar, Sep 06 2012

Also period of squares mod 10^n. - Mohammed Yaseen, Apr 18 2023

Examples

			a(2) = 50 because 11^50 = 11739085287969531650666649599035831993898213898723001 = 1 mod 1000.
		

Links

• Index entries for linear recurrences with constant coefficients, signature (10).

Crossrefs

Cf. A001020, A216099.

Programs

Mathematica

Join[{10}, NestList[10*# &, 50, 20]] (* Paolo Xausa, Feb 20 2024 *)

Formula

a(n) = 5*10^(n-1), n >= 2.