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 A300329 #22 Mar 04 2018 10:30:20 %S A300329 2,4,2,0,6,20,18,0,56,204,186,0,630,2340,2182,0,7710,29120,27594,0, %T A300329 99858,381300,364722,0,1342176,5162220,4971008,0,18512790,71582716, %U A300329 69273666,0,260300986,1010580540,981706806,0,3714566310,14467258260,14096302710,0 %N A300329 Number of solutions to +-1 +- 2 +- 3 +- ... +- n == n-1 (mod n). %H A300329 Seiichi Manyama, <a href="/A300329/b300329.txt">Table of n, a(n) for n = 1..3333</a> %e A300329 Solutions for n = 7: %e A300329 -------------------------------------------------------------- %e A300329 1 +2 +3 +4 -5 -6 +7 = 6, -1 +2 +3 -4 +5 -6 +7 = 6, %e A300329 1 +2 +3 +4 -5 -6 -7 = -8, -1 +2 +3 -4 +5 -6 -7 = -8, %e A300329 1 +2 +3 -4 +5 +6 +7 = 20, -1 +2 -3 +4 +5 +6 +7 = 20, %e A300329 1 +2 +3 -4 +5 +6 -7 = 6, -1 +2 -3 +4 +5 +6 -7 = 6, %e A300329 1 +2 -3 -4 -5 -6 +7 = -8, -1 -2 +3 -4 -5 -6 +7 = -8, %e A300329 1 +2 -3 -4 -5 -6 -7 = -22, -1 -2 +3 -4 -5 -6 -7 = -22, %e A300329 1 -2 +3 -4 -5 +6 +7 = 6, -1 -2 -3 +4 -5 +6 +7 = 6, %e A300329 1 -2 +3 -4 -5 +6 -7 = -8, -1 -2 -3 +4 -5 +6 -7 = -8, %e A300329 1 -2 -3 +4 +5 -6 +7 = 6, %e A300329 1 -2 -3 +4 +5 -6 -7 = -8. %o A300329 (PARI) a(n) = my (v=vector(n, k, k==1)); for (p=1, n, v = vector(n, k, v[1+(k-1+p)%n]+v[1+(k-1-p)%n])); v[1+(n-1)%n] \\ _Rémy Sigrist_, Mar 03 2018 %Y A300329 Cf. A300190, A300328. %K A300329 nonn %O A300329 1,1 %A A300329 _Seiichi Manyama_, Mar 03 2018