I'm trying to understand the formula presented for the sequence A064532 from the OEIS, looks like a recurrence relation with complex numbers:$a(10i+j) = a(i) + a(j), etc.$Sorry if its a simple equation, but I wasn't able to understand it....Read more

I'm looking for the number of unlabeled hypergraphs on n nodes and stumbled upon the comments of A003180 in OEIS. Can somebody please explain to me how that sequence relates to the number of unlabeled hypergraphs?For example, I think there should be 6 unlabeled hypergraphs on 2 nodes, the edge set could consist of: nothing1 node2 nodesnothing + 1 edge ("edge" meaning edge containing all two nodes)1 node + 1 edge 2 nodes + 1 edge But the sequence claims it should be 4....Read more

I've just read this interesting article: http://arxiv.org/pdf/1101.4470.pdfWhere I found this graph representing $N(n)$ the number of occurrences of every integer $n$ in the Sloane encyclopedia of integer sequence (OEIS):I would like the list of values of $N(n)$ for every integer $n$ up to $5050$....Read more

In 1971 Richard Guy sent a letter to Neil Sloane outlining some integer sequences. One of these sequences, A279196, was added to the OEIS by Neil only in December of 2016: A279196: Number of polynomials $P(x,y)$ with nonnegative integer coefficients such that $P(x,y) \equiv 1 \text{ (mod } x+y-1)$ and $P(1,1) = n$.The first few terms of the sequence are: 1, 1, 2, 5, 13, 36, 102, 295, 864In a recent lecture (see 9:50), Neil said: I don't even know what the [...] polynomials are for the first few values, so it might be interesting to look into...Read more

Do you know what it is that those numbers which appear in the upper-right angle of the blue-box mean?I presume they have to do with a certain ranking of the sequences within the site, but I am not sure.Thanks in advance for your replies....Read more