OFFSET
0,8
LINKS
EXAMPLE
The array begins as:
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ...
0, 2, 1, 6, 8, 7, 3, 5, 4, 18, 20, 19, 24, ...
0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, ...
0, 4, 8, 12, 16, 11, 24, 19, 23, 36, 40, 44, 48, ...
0, 5, 7, 15, 11, 13, 21, 26, 19, 45, 50, 52, 33, ...
0, 6, 3, 18, 24, 21, 9, 15, 12, 54, 60, 57, 72, ...
0, 7, 5, 21, 19, 26, 15, 13, 11, 63, 70, 68, 57, ...
0, 8, 4, 24, 23, 19, 12, 11, 16, 72, 80, 76, 69, ...
0, 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99, 108, ...
0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 83, 120, ...
0, 11, 19, 33, 44, 52, 57, 68, 76, 99, 83, 91, 132, ...
0, 12, 24, 36, 48, 33, 72, 57, 69, 108, 120, 132, 144, ...
etc.
A(2,2) = 2*2 mod 3 = 1.
PROG
(PARI)
up_to = 105;
A325820sq(b, c) = fromdigits(Vec(Pol(digits(b, 3))*Pol(digits(c, 3)))%3, 3);
A325820list(up_to) = { my(v = vector(up_to), i=0); for(a=0, oo, for(col=0, a, if(i++ > up_to, return(v)); v[i] = A325820sq(a-col, col))); (v); };
v325820 = A325820list(up_to);
A325820(n) = v325820[1+n];
CROSSREFS
KEYWORD
AUTHOR
Antti Karttunen, May 22 2019
STATUS
approved