This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A130079 #9 Oct 02 2017 08:26:07 %S A130079 3,2,4,3,3,2,4,4,4,3,5,3,2,2,5,2,4,3,5,4,4,3,5,5,5,4,6,3,4,2,6,5,4,3, %T A130079 5,4,4,3,5,5,5,4,6,4,3,3,6,0,5,4,6,5,5,4,6,6,6,5,7,3,5,2,7,6,4,3,5,4, %U A130079 4,3,5,5,5,4,6,4,1,3,6,4,5,4,6,5,5,4,6,6,6,5,7,4,5,3,7,6,5,4 %N A130079 a(n) = n - A130077(n), i.e., n minus the largest x such that 2^x divides A001623(n), the number of reduced three-line Latin rectangles. %H A130079 John Riordan, <a href="http://www.jstor.org/stable/2308187">A recurrence relation for three-line Latin rectangles</a>, Amer. Math. Monthly, 59 (1952), pp. 159-162. %H A130079 D. S. Stones, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v17i1a1/0">The many formulas for the number of Latin rectangles</a>, Electron. J. Combin 17 (2010), A1. %H A130079 D. S. Stones and I. M. Wanless, <a href="http://dx.doi.org/10.1016/j.jcta.2009.03.019">Divisors of the number of Latin rectangles</a>, J. Combin. Theory Ser. A 117 (2010), 204-215. %o A130079 (PARI) a001623(n) = n*(n-3)!*sum(i=0, n, sum(j=0, n-i, (-1)^j*binomial(3*i+j+2, j)<<(n-i-j)/(n-i-j)!)*i!); %o A130079 a(n) = n - valuation(a001623(n), 2); \\ _Michel Marcus_, Oct 02 2017 %Y A130079 Cf. A001623, A130077, A130078. %K A130079 nonn %O A130079 3,1 %A A130079 Douglas Stones (dssto1(AT)student.monash.edu.au), May 06 2007