The homepage of the Journal of Integer Sequences says:
If there are accompanying style files or diagrams, please be sure to include them. Diagrams should be prepared in .ps (postscript) or .eps format, not pdf or other formats. If there are multiple files, please consider sending them as a Unix tar or zip file.
Does this mean that preparing diagrams using TikZ is allowed or not?
What about preparing them as an image (say, .jpg or .gif) and including them?