login
A053793
n^2+n modulo 7.
3
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.
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
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