Extensions

Extensions to an OEIS sequence entry consist of anything added by anyone at any time other than the original contributor at the original date given in the Author field. All extensions, except the most minor, are acknowledged, if not in the relevant field, in the Extensions field. The most common use of the Extensions field is to acknowledge additional terms, as it would be awkward to give credit in the Data field:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47 - more terms from Tom Tomsson, Jan 24 2010, 53, 59, 61, 67 - additional terms from Sally Sallinen, Feb 28 2010

Instead the Extensions field would say something like:

a(13)-a(15) from Tom Tomsson, Jan 24 2010; a(16)-a(19) from Sally Sallinen, Feb 28 2010

Note that additions from the original contributor count as extensions if made after the initial contribution.

The following table explains which fields can have extensions acknowledged within them and which require the use of the Extensions field:

Field	Action	Notation in Extensions field
Name	Simplified or corrected the definition	Simplified definition or Corrected definition followed by contributor's name and date
Data	Added terms, including an initial term overlooked by the original contributor	Something like a(12)-a(14) from followed by contributor's name and date.
Offset	Adjusted or corrected offset	Adjusted offset from or Corrected offset from followed by old value, new value and contributor's name and date
Comments	Added comments	None needed, contributor should be acknowledged in Comments field.
References	Added references	None needed
Links	Removed or updated broken links	None needed
Example	Corrected an example.	None needed, but may claim credit in Extensions field if desired.
Maple	Added a Maple program	None, use Maple comment syntax to claim credit in Maple field.
Mathematica	Added a Wolfram Mathematica program	None, use Mathematica comment syntax to claim credit in Mathematica field.
Prog	Added a program in a programming language or for a computer algebra system other than Maple or Mathematica	None, use a comment (if available) in the Prog field.
Crossrefs	Added cross-references	None needed
Keyword	Added or removed keywords	List which keywords were added and/or removed, followed by contributor's name and date
Author	N/A	N/A
Extensions	N/A	N/A

OEIS sequence entry fields

Name · Data · Offset · Comments · References · Example · Maple · Mathematica · Prog · Crossrefs · Keyword · Author · Extensions