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A211509 Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2=2n-x*y. 2
0, 1, 0, 2, 3, 4, 4, 4, 8, 7, 6, 10, 10, 8, 16, 10, 11, 16, 14, 8, 22, 12, 18, 24, 18, 13, 26, 18, 20, 24, 24, 10, 36, 22, 20, 30, 29, 20, 42, 20, 22, 30, 36, 24, 44, 24, 28, 40, 38, 15, 48, 26, 34, 48, 38, 18, 50, 38, 42, 38, 44, 18, 66, 42, 35, 50, 38, 32, 68, 24, 36 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

For a guide to related sequences, see A211422.

LINKS

Table of n, a(n) for n=0..70.

MATHEMATICA

t[n_] := t[n] = Flatten[Table[w^2 + x*y - 2 n, {w, 1, n}, {x, 1, n}, {y, 1, n}]]

c[n_] := Count[t[n], 0]

t = Table[c[n], {n, 0, 70}]  (* A211509 *)

CROSSREFS

Cf. A211422.

Sequence in context: A108355 A057951 A076410 * A305594 A320778 A058277

Adjacent sequences:  A211506 A211507 A211508 * A211510 A211511 A211512

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 14 2012

STATUS

approved

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Last modified February 22 05:17 EST 2019. Contains 320385 sequences. (Running on oeis4.)