This site is supported by donations to The OEIS Foundation.
User:Enrique Pérez Herrero/OEIS2BibTeX
From OeisWiki
OEIS2BibTeX
This is a small PHP application to get fast BiTeX citation to OEIS sequences.
For more information, please visit:
Psychedelic Geometry: BibTeX Automatic OEIS Citations
To get citations by parameters supplied within the link, you can use for example, if you wish to cite the sequence A000340:
http://www.oeis2bibtex.netai.net/OEIS2BibTeX.php?sequence=A000340
OEIS2BibTeX PHP Code
<?php
//Classic OEIS url.
$oeis_url = "http://www.research.att.com/~njas/sequences/";
//Wiki OEIS url.
$wiki_oeis_url = "http://oeis.org/wiki/";
function validate_sequence($s)
{
if (strlen($s)!=7)
{
print("ERROR-1: Bad Sequence Id length!");
return false;
}
$permitted = "0123456789";
for ($i=1; $i<strlen($s); $i++)
{
if (strpos($permitted, substr($s,$i,1))===false)
{
print("ERROR-2: Wrong characters on input string!");
return false;
}
}
if (strpos("A", substr($s,0,1))===false)
{
print("ERROR-3: Sequence Id does not begin with A.");
return false;
}
return true;
}
$OEIS_Id=strtoupper($_POST["sequence"]);
if (!$OEIS_Id) $OEIS_Id=$_GET{sequence};
if(validate_sequence($OEIS_Id))
{
$url1 = $oeis_url.$OEIS_Id;
$url2 = $wiki_oeis_url.$OEIS_Id;
//echo "$url1"."<br/>";
//echo "$url2"."<br/>";
$page_url = @fopen($url2, "r");
if($page_url)
{
$OEIS_Text="";
while(!feof($page_url))
{
$OEIS_Text .= fgetss($page_url, 1024);
}
//echo $OEIS_Text."<br/>"."<br/>";
// Search the sequence description.
$d1 = strpos($OEIS_Text,", search")+strlen(", search");
$d2 = strpos($OEIS_Text,"classic");
$OEIS_Description=trim(substr($OEIS_Text,$d1,$d2-$d1));
// Search the sequence Author.
$a1 = strrpos($OEIS_Text,"Author")+strlen("Author");
$a2 = strrpos($OEIS_Text,"Retrieved");
$OEIS_Author=substr($OEIS_Text,$a1,$a2-$a1);
//Removing Author´s email.
$e = strpos($OEIS_Author,"(");
$OEIS_Author=substr($OEIS_Author,1,$e-2);
echo "@MISC{oeis".$OEIS_Id.",<br/>".
"AUTHOR = {".$OEIS_Author."},<br/>".
"TITLE = {The {O}n-{L}ine {E}ncyclopedia of {I}nteger {S}equences},<br/>".
"HOWPUBLISHED = {\href{".$url2."}{".$OEIS_Id."}},<br/>".
"MONTH={},<br/>".
"YEAR ={},<br/>".
"NOTE = {".$OEIS_Description."}<br/>}";
}
else {print("ERROR4-Sequence does not exists");}
}
@fclose($page_url);
?>
OEIS2BibTeX KNOWN ISSUES
- The code can not find the AUTHOR when there are more than one.
- The code can not find the AUTHOR when no email is supplied.
- MONTH and YEAR are not implemented.
