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A070440 a(n) = n^2 mod 18. 2
0, 1, 4, 9, 16, 7, 0, 13, 10, 9, 10, 13, 0, 7, 16, 9, 4, 1, 0, 1, 4, 9, 16, 7, 0, 13, 10, 9, 10, 13, 0, 7, 16, 9, 4, 1, 0, 1, 4, 9, 16, 7, 0, 13, 10, 9, 10, 13, 0, 7, 16, 9, 4, 1, 0, 1, 4, 9, 16, 7, 0, 13, 10, 9, 10, 13, 0, 7, 16, 9, 4, 1, 0, 1, 4, 9, 16, 7, 0, 13, 10, 9, 10, 13, 0, 7, 16, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

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, 1).

FORMULA

a(n) = a(n-18). - R. J. Mathar, Jul 27 2015

G.f.: -x*(1 +4*x +9*x^2 +16*x^3 +7*x^4 +13*x^6 +10*x^7 +9*x^8 +10*x^9 +13*x^10 +7*x^12 +16*x^13 +9*x^14 +4*x^15 +x^16) / ( (x-1)*(1+x+x^2)*(1+x^3+x^6)*(1+x)*(1-x+x^2)*(1-x^3+x^6) ). - R. J. Mathar, Jul 27 2015

MATHEMATICA

Table[Mod[n^2, 18], {n, 0, 200}] (* Vladimir Joseph Stephan Orlovsky, Apr 23 2011 *)

PROG

(PARI) a(n)=n^2%18 \\ Charles R Greathouse IV, Apr 06 2016

CROSSREFS

Cf. A070441, A070442.

Sequence in context: A086957 A096879 A070441 * A054580 A165488 A313300

Adjacent sequences:  A070437 A070438 A070439 * A070441 A070442 A070443

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, May 12 2002

STATUS

approved

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Last modified October 16 03:52 EDT 2021. Contains 348035 sequences. (Running on oeis4.)