The On-Line Encyclopedia of Integer Sequences (OEIS)

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A211508

Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2=n-x*y.
(history; published version)

#4 by T. D. Noe at Thu Apr 19 17:39:20 EDT 2012

STATUS

proposed

approved

#3 by Clark Kimberling at Thu Apr 19 17:18:46 EDT 2012

STATUS

editing

proposed

#2 by Clark Kimberling at Sat Apr 14 10:34:21 EDT 2012

NAME

allocated for Clark KimberlingNumber of ordered triples (w,x,y) with all terms in {1,...,n} and w^2=n-x*y.

DATA

0, 0, 1, 2, 2, 4, 4, 6, 5, 6, 8, 8, 8, 12, 8, 10, 12, 12, 11, 16, 12, 16, 16, 12, 16, 20, 14, 16, 22, 20, 16, 24, 17, 22, 24, 16, 22, 30, 16, 24, 30, 26, 20, 28, 26, 28, 32, 18, 26, 38, 21, 30, 36, 28, 28, 34, 30, 36, 34, 26, 34, 46, 20, 28, 46, 36, 32, 40, 30, 42, 40

OFFSET

0,4

COMMENTS

For a guide to related sequences, see A211422.

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}] (* A211508 *)

CROSSREFS

Cf. A211422.

KEYWORD

allocated

nonn

AUTHOR

Clark Kimberling, Apr 14 2012

STATUS

approved

editing

#1 by Clark Kimberling at Fri Apr 13 17:53:40 EDT 2012

NAME

allocated for Clark Kimberling

KEYWORD

allocated

STATUS

approved