A331774 - OEIS

A331774

a(n) = Sum_{-n<i<n, -n<j<n, gcd{i,j}=3} (n-|i|)*(n-|j|).

0, 0, 0, 20, 56, 108, 208, 340, 504, 788, 1136, 1548, 2136, 2820, 3600, 4748, 6056, 7524, 9312, 11292, 13464, 16380, 19584, 23076, 27272, 31820, 36720, 42668, 49064, 55908, 63712, 72028, 80856, 91596, 103008, 115092, 128456, 142556, 157392, 174932, 193400

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OFFSET

1,4

LINKS

Table of n, a(n) for n=1..41.

M. A. Alekseyev, M. Basova, and N. Yu. Zolotykh. On the minimal teaching sets of two-dimensional threshold functions. SIAM Journal on Discrete Mathematics 29:1 (2015), 157-165. doi:10.1137/140978090. See p. 158.

MAPLE

VR := proc(m, n, q) local a, i, j; a:=0;

for i from -m+1 to m-1 do for j from -n+1 to n-1 do

if gcd(i, j)=q then a:=a+(m-abs(i))*(n-abs(j)); fi; od: od: a; end;

[seq(VR(n, n, 3), n=1..50)];

CROSSREFS

This is twice A177720 and 4 times A331775.

Sequence in context: A044503 A344072 A109806 * A216267 A012483 A051872

Adjacent sequences: A331771 A331772 A331773 * A331775 A331776 A331777

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 08 2020

STATUS

approved