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A320313
Number of ways to write n as the sum of 4 positive integers a, b, c, d such that d < b and a/b - c/d = (a - c)/(b - d).
5
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 2, 0, 2, 0, 1, 1, 0, 1, 1, 2, 1, 1, 2, 0, 2, 1, 3, 1, 2, 2, 1, 1, 2, 3, 2, 2, 3, 2, 2, 1, 4, 1, 4, 2, 2, 3, 5, 3, 3, 2, 5, 1, 4, 2, 4, 5, 4, 3, 3, 4, 4, 3, 3, 3, 6, 2, 5, 4, 7, 3, 9, 3, 4, 3, 5
OFFSET
1,22
LINKS
PROG
(PARI) m=86; v=vector(m); for(a=1, m, for(b=1, m, for(c=1, m, for(d=1, b-1, n=a+b+c+d; if(n<=m, if(a/b-c/d==(a-c)/(b-d), v[n]++)))))); v
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Oct 10 2018
STATUS
approved