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A211506 Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2=x*y+n. 3
0, 0, 2, 3, 2, 5, 6, 7, 9, 11, 10, 9, 13, 17, 14, 14, 29, 17, 18, 25, 21, 28, 26, 17, 32, 59, 24, 28, 39, 37, 28, 41, 36, 42, 50, 28, 91, 55, 26, 44, 66, 55, 40, 57, 59, 67, 70, 31, 65, 151, 48, 62, 85, 57, 68, 70, 78, 84, 72, 55, 92, 115, 38, 71, 210, 88, 80, 89 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

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}]  (* A211506 *)

CROSSREFS

Cf. A211422.

Sequence in context: A097448 A066729 A241592 * A182880 A182898 A133684

Adjacent sequences:  A211503 A211504 A211505 * A211507 A211508 A211509

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 14 2012

STATUS

approved

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Last modified October 22 17:39 EDT 2019. Contains 328319 sequences. (Running on oeis4.)