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 A302290 #30 Aug 23 2018 17:36:44
%S A302290 1,2,1,2,4,2,1,4,5,2,4,8,4,2,5,6,5,4,8,10,5,4,9,10,4,8,16,8,4,10,9,6,
%T A302290 9,12,12,12,9,8,13,12,8,16,20,10,9,14,13,12,12,18,21,12,9,18,20,8,16,
%U A302290 32,16,8,20,18,9,14,25,20,16,20,17,16,17,20,24,24,24,20,17,18,21,22,20,28,29,16,17,28,24
%N A302290 a(n) is the 2-norm of denominators of two-variable polynomials of degree n which are integer-valued.
%C A302290 This is the 2-sequence of integer-valued polynomials of 2-variables. It can be shown that this also the 2-sequence of the homogeneous 3-variable integer valued polynomials where one of the variables is restricted to evaluate at odd values.
%C A302290 a(n) is also the n-th Bhargava's factorial when generalized to the two-variable case.
%H A302290 M. Bhargava, <a href="https://doi.org/10.1090/S0894-0347-09-00638-9">On P-orderings, Integer-Valued Polynomials, and Ultrametric Analysis</a>, J. Amer. Math. Soc., 22 (2009), 963-993.
%H A302290 S. Evrard, <a href="https://doi.org/10.1016/j.jalgebra.2012.09.013">Bhargava's factorial in several variables</a>, Journal of Algebra, 372 (2012), 134-148.
%F A302290 a(n) = 2^{k-1} if n = 2^k-k-1
%F A302290 a(2(2^k-k-1)-n) if 2^k-k-1 < n < 2^k-1
%F A302290 a(2(2^k-k-1)-n)+ 2a(n-2^k+1) if 2^k-1 <= n <= 2(2^k-k-1)
%F A302290 2a(n-2^k+1) if 2(2^k-k-1) < n < 2^{k+1}-k-2
%F A302290 where k is such that 2^k-k-1<= n.
%Y A302290 Cf. A212429.
%K A302290 nonn
%O A302290 0,2
%A A302290 _Marie-Andree B.Langlois_, Apr 04 2018