login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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: A228576 A329465 A324195 * A295368 A283832 A102086

Adjacent sequences:  A211504 A211505 A211506 * A211508 A211509 A211510

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 14 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 10 15:09 EST 2019. Contains 329896 sequences. (Running on oeis4.)