Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A018809
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A018809 Number of lines through exactly 2 points of an n X n grid of points. +0
3
0, 0, 6, 12, 48, 108, 248, 428, 764, 1196, 1900, 2668, 3824, 5244, 7248, 9380, 12192, 15372, 19528, 24020, 29732, 36052, 43808, 51836, 61636, 72492, 85308, 98492, 114012, 130668, 150196, 170828, 194768, 220276, 249452, 279284, 312572, 348036 (list; graph; listen)
OFFSET

0,3

FORMULA

1/2 (f(n, 4) - 2 f(n, 3) + f(n, 2)) where f(n, k) = Sum ((n - |x|)(n - |y|)); -n<x<n, -n<y<n, (x, y)=k.

CROSSREFS

Sequence in context: A052904 A106692 A032470 this_sequence A117866 A094060 A076722

Adjacent sequences: A018806 A018807 A018808 this_sequence A018810 A018811 A018812

KEYWORD

nonn

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified December 2 15:58 EST 2008. Contains 150992 sequences.


AT&T Labs Research