Sierpiński, Wacław Cardinal and ordinal numbers. 2nd ed. revised. (English) Zbl 0131.24801 Monografie Matematyczne. Tom 34. Warszawa: Panstwowe Wydawnictwo Naukowe. 491 p. (1965). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 72 Documents Keywords:set theory PDFBibTeX XML Online Encyclopedia of Integer Sequences: Number of ways to add n ordinals.