The On-Line Encyclopedia of Integer Sequences (OEIS)

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A212021

Number of (w,x,y,z) with all terms in {1,...,n} and 2w*x=3*y*z.
(history; published version)

#7 by N. J. A. Sloane at Sun Dec 04 19:46:28 EST 2016

MATHEMATICA

(* _Peter J. C. Moses, _, Apr 13 2012 *)

Discussion

Sun Dec 04

19:46

OEIS Server: https://oeis.org/edit/global/2576

#6 by Alois P. Heinz at Sun May 13 11:06:11 EDT 2012

STATUS

proposed

approved

#5 by Clark Kimberling at Sun May 13 10:04:25 EDT 2012

STATUS

editing

proposed

#4 by Clark Kimberling at Sun May 13 10:04:20 EDT 2012

MATHEMATICA

(Do[If[2 w*x == 3 y*z, s = s + 1],

Map[t[#] &, Range[0, 50]] (* A212020 A212021 *)

STATUS

proposed

editing

#3 by Clark Kimberling at Sat May 12 16:34:37 EDT 2012

STATUS

editing

proposed

Discussion

Sat May 12

21:44

Alois P. Heinz: Here the terms match the definition in name but the program seems to be incorrect, it has another A-number and contains another condition (w*x == 3 y*z) than in name (2w*x=3*y*z).

#2 by Clark Kimberling at Sat Apr 28 19:33:47 EDT 2012

NAME

allocated for Clark KimberlingNumber of (w,x,y,z) with all terms in {1,...,n} and 2w*x=3*y*z.

DATA

0, 0, 0, 8, 16, 20, 48, 56, 80, 132, 164, 176, 272, 288, 332, 436, 512, 532, 696, 720, 844, 1000, 1076, 1104, 1360, 1430, 1518, 1758, 1942, 1978, 2328, 2368, 2566, 2818, 2938, 3098, 3600, 3648, 3780, 4084, 4440, 4492, 4996, 5052, 5348, 5920

OFFSET

0,4

COMMENTS

Each term is divisible by 2. See A211795 for a guide to related sequences.

MATHEMATICA

t = Compile[{{n, _Integer}}, Module[{s = 0},

(Do[If[w*x == 3 y*z, s = s + 1],

{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];

Map[t[#] &, Range[0, 50]] (* A212020 *)

%/2 (* integers *)

(* Peter Moses, Apr 13 2012 *)

CROSSREFS

Cf. A211795.

KEYWORD

allocated

nonn

AUTHOR

Clark Kimberling, Apr 28 2012

STATUS

approved

editing

Discussion

Sat May 05

23:55

OEIS Server: This sequence has not been edited or commented on for a week
yet is not proposed for review.  If it is ready for review, please
visit https://oeis.org/draft/A212021 and click the button that reads
"These changes are ready for review by an OEIS Editor."

Thanks.
  - The OEIS Server

#1 by Clark Kimberling at Thu Apr 26 20:34:50 EDT 2012

NAME

allocated for Clark Kimberling

KEYWORD

allocated

STATUS

approved