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 A320311 Number of ways to write n as the sum of 4 positive integers a, b, c, d such that 1 - a/c = (1 - b/d)^2. 4
 0, 0, 0, 1, 0, 2, 0, 3, 0, 5, 0, 6, 1, 6, 0, 8, 2, 9, 2, 10, 0, 15, 1, 14, 1, 15, 3, 15, 2, 17, 4, 19, 3, 21, 1, 21, 4, 26, 3, 25, 4, 24, 4, 27, 6, 29, 5, 31, 5, 30, 4, 36, 4, 37, 6, 34, 6, 41, 8, 36, 8, 43, 4, 42, 5, 44, 10, 44, 9, 45, 9, 45, 10, 48 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS PROG (PARI) m=74; v=vector(m); for(a=1, m, for(b=1, m, for(c=1, m, for(d=1, m, n=a+b+c+d; if(n<=m, if(1-a/c==(1-b/d)^2, v[n]++)))))); v CROSSREFS Cf. A026810, A319853, A319854, A320312, A320313. Sequence in context: A008820 A066682 A239968 * A240140 A240141 A049641 Adjacent sequences:  A320308 A320309 A320310 * A320312 A320313 A320314 KEYWORD nonn AUTHOR Hugo Pfoertner and Rainer Rosenthal Oct 10 2018 STATUS approved

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Last modified August 2 02:40 EDT 2021. Contains 346409 sequences. (Running on oeis4.)