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 A359860 #15 Oct 11 2024 13:57:35 %S A359860 3,45,231,865,2081,4489,8211,14401,22857,35445,51741,74397,102271, %T A359860 138801,182739,238181,303175,383097,474995,586021,712003,860829, %U A359860 1028225,1223773,1440593,1689993,1965525,2279509,2622993,3011405,3433615,3907241,4419261,4988781,5603271 %N A359860 Number of regions among all distinct circles that can be constructed from a 2 X n square grid of points using only a compass. %C A359860 See A359859 for further details. No formula for a(n) is known. %H A359860 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A359859%2B60%2B61.py">Python program</a>. %H A359860 Scott R. Shannon, <a href="/A359860/a359860.jpg">Image for n = 1</a>. %H A359860 Scott R. Shannon, <a href="/A359860/a359860_1.jpg">Image for n = 2</a>. %H A359860 Scott R. Shannon, <a href="/A359860/a359860_2.jpg">Image for n = 3</a>. %H A359860 Scott R. Shannon, <a href="/A359860/a359860_3.jpg">Image for n = 4</a>. %H A359860 Scott R. Shannon, <a href="/A359860/a359860_4.jpg">Image for n = 5</a>. %H A359860 Scott R. Shannon, <a href="/A359860/a359860_5.jpg">Image for n = 8</a>. %F A359860 a(n) = A359861(n) - A359859(n) + 1 by Euler's formula. %Y A359860 Cf. A359859 (vertices), A359861 (edges), A359862 (k-gons), A001859, A359253. %K A359860 nonn %O A359860 1,1 %A A359860 _Scott R. Shannon_, Jan 16 2023 %E A359860 a(19)-a(35) from _Lucas A. Brown_, Oct 11 2024