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A333462
a(n) is the number of Gaussian integers z such that (n-1)/2 < |z| <= n/2, divided by 4.
4
0, 1, 1, 1, 2, 2, 2, 3, 5, 3, 4, 4, 6, 3, 7, 5, 7, 7, 10, 6, 8, 7, 11, 5, 12, 10, 12, 9, 13, 11, 10, 12, 16, 10, 18, 9, 19, 11, 18, 14, 14, 15, 21, 15, 20, 14, 22, 13, 23, 19, 23, 17, 24, 18, 22, 19, 27, 17, 26, 22, 28, 17, 31, 21, 26, 24, 28, 26, 30, 27, 29, 21
OFFSET
1,5
LINKS
PROG
(PARI) c=vectorsmall(2000000); for(x=1, 1000, my(x2=x*x); c[x2]++; c[x2+x2]++; for(y=1, x-1, my(y2=y*y); c[x2+y2]+=2));
a(n)=sum(k=ceil((1+(n-1)^2)/4), floor(n^2/4), c[k]);
for(k=1, 72, print1(a(k), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Mar 26 2020
STATUS
approved