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 A331395 #9 Oct 15 2024 18:06:54 %S A331395 1,3,5,21,17,281,65,3209,10853,47617,1025,3610317,4097,22361569, %T A331395 570275061,2515267681,65537,229801424781,262145,10805763650257, %U A331395 114290395025669,39654899669089,4194305,150858428803209493,140094551951590929,98672497472409697 %N A331395 Number of nonnegative integer matrices with total sum n, nonzero rows and distinct columns each with the same sum with columns in decreasing lexicographic order. %C A331395 The condition that the columns be in decreasing order is equivalent to considering nonequivalent matrices with distinct columns up to permutation of columns. %H A331395 Andrew Howroyd, <a href="/A331395/b331395.txt">Table of n, a(n) for n = 1..200</a> %F A331395 a(n) = Sum_{d|n} A331278(n/d, d). %F A331395 a(p) = 2^(p-1) + 1 for prime p. %Y A331395 Cf. A331278. %K A331395 nonn %O A331395 1,2 %A A331395 _Andrew Howroyd_, Jan 15 2020