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A047210 Largest square modulo n. 4
0, 1, 1, 1, 4, 4, 4, 4, 7, 9, 9, 9, 12, 11, 10, 9, 16, 16, 17, 16, 18, 20, 18, 16, 24, 25, 25, 25, 28, 25, 28, 25, 31, 33, 30, 28, 36, 36, 36, 36, 40, 39, 41, 37, 40, 41, 42, 36, 46, 49, 49, 49, 52, 52, 49, 49, 55, 57, 57, 49, 60, 59, 58, 57, 64, 64, 65, 64, 64, 65, 64, 64, 72 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

Eric Weisstein's World of Mathematics, Quadratic Residue

MATHEMATICA

Table[r=Range[n]; Max[Mod[r^2, n]], {n, 100}] (* T. D. Noe, Dec 18 2008 *)

Table[r = Range[1 + n/2]; Max[Mod[r^2, n]], {n, 100}] (* Zak Seidov, Dec 18 2008 *)

PROG

Contribution from Michael B. Porter, May 04 2010: (Start)

(PARI) residue(n, m)={local(r); r=0; for(i=0, floor(m/2), if(i^2%m==n, r=1)); r}

A047210(n)={local(r, m); r=0; m=n; while(r==0, m=m-1; if(residue(m, n), r=1)); m} (End)

CROSSREFS

Last elements of rows of A096008.

Sequence in context: A106325 A159835 A240835 * A120327 A056629 A245356

Adjacent sequences: A047207 A047208 A047209 * A047211 A047212 A047213

KEYWORD

easy,nonn

AUTHOR

Henry Bottomley, Jun 08 2000

STATUS

approved

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Last modified December 1 23:44 EST 2022. Contains 358485 sequences. (Running on oeis4.)