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 A211507 Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2=x*y-n. 2
 0, 0, 0, 1, 2, 3, 4, 3, 9, 9, 4, 17, 11, 7, 18, 16, 19, 21, 16, 21, 35, 24, 8, 35, 42, 17, 44, 40, 25, 47, 28, 47, 56, 28, 30, 76, 69, 11, 52, 68, 54, 81, 36, 33, 99, 61, 38, 99, 77, 51, 76, 88, 63, 67, 92, 88, 140, 40, 12, 153, 90, 71, 98, 121, 98, 104, 100, 41 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS For a guide to related sequences, see A211422. LINKS Table of n, a(n) for n=0..67. MATHEMATICA t[n_] := t[n] = Flatten[Table[w^2 - x*y + n, {w, 1, n}, {x, 1, n}, {y, 1, n}]] c[n_] := Count[t[n], 0] t = Table[c[n], {n, 0, 80}] (* A211507 *) CROSSREFS Cf. A211422. Sequence in context: A329465 A324195 A339663 * A295368 A283832 A102086 Adjacent sequences: A211504 A211505 A211506 * A211508 A211509 A211510 KEYWORD nonn AUTHOR Clark Kimberling, Apr 14 2012 STATUS approved

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Last modified May 29 22:36 EDT 2024. Contains 372954 sequences. (Running on oeis4.)