This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A087735 Array read by antidiagonals: T(n,k) = o(n,k), where o(,) is a binary operation arising from counting the elements that are sums of m squares in a field of characteristic not equal to 2. 0
 1, 2, 2, 3, 2, 3, 4, 4, 4, 4, 5, 4, 4, 4, 5, 6, 6, 4, 4, 6, 6, 7, 6, 7, 4, 7, 6, 7, 8, 8, 8, 8, 8, 8, 8, 8, 9, 8, 8, 8, 8, 8, 8, 8, 9, 10, 10, 8, 8, 8, 8, 8, 8, 10, 10, 11, 10, 11, 8, 8, 8, 8, 8, 11, 10, 11, 12, 12, 12, 12, 8, 8, 8, 8, 12, 12, 12, 12, 13, 12, 12, 12, 13, 8, 8, 8, 13, 12, 12, 12, 13 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The array is symmetric (there is an error in the published version of the Allouche-Shallit paper). REFERENCES J.-P. Allouche and J. Shallit, The ring of k-regular sequences, II, Theoret. Computer Sci., 307 (2003), 3-29. A. Pfister, Zur Darstellung von -1 als Summe von Quadraten in einem Koerper, J. London Math. Soc. 40 1965 159-165. A. Pfister, Quadratische Formen in beliebigen Koerpern, Invent. Math. 1 1966 116-132. D. B. Shapiro, Products of sums of squares, Expos. Math., 2 (1984), 235-261. LINKS J.-P. Allouche, J. Shallit, The Ring of k-regular Sequences, II J.-P. Allouche, J. Shallit, The Ring of k-regular Sequences, II (preprint), ex. 25. A. Pfister, Quadratische Formen in beliebigen Koerpern, Invent. Math. 1 1966 116-132. FORMULA T(2m, 2n) = 2T(m, n), T(2m-1, 2n) = 2T(m, n), T(2m, 2n-1) = 2T(m, n), T(2m-1, 2n-1) = 2T(m, n) - (binomial(m+n-2, m-1) mod 2). CROSSREFS Sequence in context: A249871 A074712 A271914 * A277194 A172151 A106250 Adjacent sequences:  A087732 A087733 A087734 * A087736 A087737 A087738 KEYWORD nonn,tabl AUTHOR N. J. A. Sloane, Oct 01 2003 EXTENSIONS More terms from Pab Ter (pabrlos(AT)yahoo.com), May 27 2004 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 23 17:24 EST 2019. Contains 319399 sequences. (Running on oeis4.)