A320311 - OEIS

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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.

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

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OFFSET

1,6

LINKS

Table of n, a(n) for n=1..74.

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: A066682 A239968 A362369 * A240140 A240141 A049641

Adjacent sequences: A320308 A320309 A320310 * A320312 A320313 A320314

KEYWORD

nonn

AUTHOR

Hugo Pfoertner and Rainer Rosenthal Oct 10 2018

STATUS

approved