A053793 n^2+n modulo 7.

0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0, 0, 2, 6, 5, 6, 2, 0

Offset

0,2

Comments

Pronic residues (mod m) are analogous to quadratic residues.

Periodic with period 7.

Links

Table of n, a(n) for n=0..104.

Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 1).

Mathematica

Table[Mod[n^2+n, 7], {n, 0, 120}] (* Harvey P. Dale, Aug 26 2012 *)
LinearRecurrence[{0, 0, 0, 0, 0, 0, 1}, {0, 2, 6, 5, 6, 2, 0}, 105] (* Ray Chandler, Aug 26 2015 *)

Prog

(PARI) A053793(n)=[0, 2, 6, 5, 6, 2, 0][n%7+1] \\ - M. F. Hasler, Aug 27 2012

Crossrefs

Sequence in context: A067548 A354509 A245698 * A371324 A076187 A019655

Adjacent sequences: A053790 A053791 A053792 * A053794 A053795 A053796

Keyword

nonn,easy

Author

Stuart M. Ellerstein (ellerstein(AT)aol.com), Mar 27 2000

Extensions

More terms from James A. Sellers, Apr 08 2000

Status

approved