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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|
- ↑ If the programming language has no comments (e.g., Malbolge), just leave the name and date after a dash.
OEIS sequence entry fields