A088666 a(n) = (n^4 + 1) mod 10.

1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2, 1, 2, 7, 2, 7, 6, 7, 2, 7, 2

Offset: 0

Author

Cino Hilliard, Nov 23 2003

Keywords

• easy
• nonn

Comments

Periodic, with period 10. - Harvey P. Dale, Jan 31 2015

Links

• Harvey P. Dale, 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, 1).

Crossrefs

Cf. A010879 (n mod 10), A002523 (n^4+1).

Programs

Magma

[(n^4+1) mod 10: n in [0..100]]; // Vincenzo Librandi, Feb 01 2015

Mathematica

PowerMod[Range[0,90],4,10]+1 (* or *) PadRight[{},100,{1,2,7,2,7,6,7,2,7,2}] (* Harvey P. Dale, Jan 31 2015 *)
LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 1},{1, 2, 7, 2, 7, 6, 7, 2, 7, 2},90] (* Ray Chandler, Aug 26 2015 *)

Formula

a(n) = A010879(A002523(n)). - Michel Marcus, Feb 01 2015

Extensions

Edited by Don Reble, May 03 2006

Name clarified by Vincenzo Librandi, Feb 01 2015