login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A001283 Triangle read by rows, in which row n consists of n(n+m) for m = 1 .. n-1. 6
6, 12, 15, 20, 24, 28, 30, 35, 40, 45, 42, 48, 54, 60, 66, 56, 63, 70, 77, 84, 91, 72, 80, 88, 96, 104, 112, 120, 90, 99, 108, 117, 126, 135, 144, 153, 110, 120, 130, 140, 150, 160, 170, 180, 190, 132, 143, 154, 165, 176, 187, 198, 209, 220, 231, 156, 168, 180 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
With a different offset: triangle read by rows: t(n, m) = T(n+1, m) = (n+1)(n+m+1) = radius of C-excircle of Pythagorean triangle with sides a=(n+1)^2-m^2, b=2*(n+1)*m and c=(n+1)^2+m^2. - Floor van Lamoen, Aug 21 2001
LINKS
FORMULA
T(n, m) = n*(n+m), n-1 >= m >= 1.
EXAMPLE
The triangle T(n, m) begins:
n\m 1 2 3 4 5 6 7 8 9 10 11 12 13 14 ...
2: 6
3: 12 15
4: 20 24 28
5: 30 35 40 45
6: 42 48 54 60 66
7: 56 63 70 77 84 91
8: 72 80 88 96 104 112 120
9: 90 99 108 117 126 135 144 153
10: 110 120 130 140 150 160 170 180 190
11: 132 143 154 165 176 187 198 209 220 231
12: 156 168 180 192 204 216 228 240 252 264 276
13: 182 195 208 221 234 247 260 273 286 299 312 325
14: 210 224 238 252 266 280 294 308 322 336 350 364 378
15: 240 255 270 285 300 315 330 345 360 375 390 405 420 435
...
[Reformatted and extended by Wolfdieter Lang, Dec 02 2014]
----------------------------------------------------------------
MATHEMATICA
Flatten[Table[n*(n+m), {n, 2, 10}, {m, n-1}]] (* T. D. Noe, Jun 27 2012 *)
CROSSREFS
Row sums are in A085788. Central column is A033581.
Sequence in context: A001284 A320142 A063931 * A106430 A106420 A308611
KEYWORD
nonn,easy,tabl
AUTHOR
EXTENSIONS
Edited comment by Wolfdieter Lang, Dec 02 2014
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 07:21 EDT 2024. Contains 370955 sequences. (Running on oeis4.)