Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A053458
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A053458 Open disk numbers (version 3): a(n)= number of points (i+j/2,j*sqrt(3)/2), i,j integers (triangular grid) contained in a open disk of diameter n, centered at (0,0). +0
1
0, 1, 1, 7, 13, 19, 31, 43, 55, 73, 85, 109, 121, 151, 169, 199, 235, 253, 295, 313, 361, 397, 433, 475, 511, 571, 595, 661, 703, 757, 817, 859, 925, 979, 1039, 1111, 1159, 1237, 1285, 1381, 1453, 1519, 1597, 1663, 1759, 1813, 1915, 1993, 2077, 2173, 2257 (list; graph; listen)
OFFSET

0,4

COMMENT

a(n)/(n/2)^2 --> Pi*2/sqrt(3)

CROSSREFS

A053416, A053456-A053459.

Sequence in context: A040038 A081765 A091180 this_sequence A040058 A023255 A122482

Adjacent sequences: A053455 A053456 A053457 this_sequence A053459 A053460 A053461

KEYWORD

easy,nonn

AUTHOR

Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Jan 13 2000

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 September 6 16:04 EDT 2008. Contains 143483 sequences.


AT&T Labs Research