A070462 a(n) = n^2 mod 40.

0, 1, 4, 9, 16, 25, 36, 9, 24, 1, 20, 1, 24, 9, 36, 25, 16, 9, 4, 1, 0, 1, 4, 9, 16, 25, 36, 9, 24, 1, 20, 1, 24, 9, 36, 25, 16, 9, 4, 1, 0, 1, 4, 9, 16, 25, 36, 9, 24, 1, 20, 1, 24, 9, 36, 25, 16, 9, 4, 1, 0, 1, 4, 9, 16, 25, 36, 9, 24, 1, 20, 1, 24, 9, 36, 25, 16, 9, 4, 1, 0, 1, 4, 9, 16

Offset: 0

Author

N. J. A. Sloane, May 12 2002

Keywords

• nonn
• easy

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).

Crossrefs

Cf. A070456, A070457.

Programs

Mathematica

Table[Mod[n^2,40],{n,0,200}] (* Vladimir Joseph Stephan Orlovsky, Apr 27 2011 *)
PowerMod[Range[0,90],2,40] (* Harvey P. Dale, Oct 20 2013 *)

PARI

a(n)=n^2%40 \\ Charles R Greathouse IV, Apr 06 2016

Formula

a(n) = a(n-20). - G. C. Greubel, Mar 25 2016