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 A342737 #33 Apr 16 2021 21:58:09 %S A342737 19,71,181,379,701,1189,1891,2861,4159,5851,8009,10711,14041,18089, %T A342737 22951,28729,35531,43471,52669,63251,75349,89101,104651,122149,141751, %U A342737 163619,187921,214831,244529,277201,313039,352241,395011,441559,492101,546859,606061,669941,738739,812701,892079 %N A342737 Number of wedged n-spheres in the homotopy type of the neighborhood complex of Kneser graph KG_{3,n}. %C A342737 KG_{3,n} is a graph whose vertex set is the collection of subsets of cardinality 3 of set {1,2,...,n+5,n+6} and two subsets are adjacent if and only if they are disjoint. For n >= 0, the neighborhood complex of KG_{3,n} is homotopy equivalent to a wedge of 1 + (n+1)*(n+3)*(n+4)*(n+6)/4 spheres of dimension n. %H A342737 Nandini Nilakantan and Anurag Singh, <a href="https://arxiv.org/abs/1807.11732">Neighborhood complexes of Kneser graphs KG_{3,k}</a>, arXiv:1807.11732 [math.CO], 2018. %H A342737 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-10,10,-5,1). %F A342737 a(n) = 1 + (n+1)*(n+3)*(n+4)*(n+6)/4. %F A342737 G.f.: (19 - 24* x + 16*x^2 - 6*x^3 + x^4)/(1 - x)^5. - _Stefano Spezia_, Mar 22 2021 %e A342737 a(0)=19 because the neighborhood complex of KG_{3,0} is the vertex set of KG_{3,0}, which is a wedge of 19 spheres of dimension 0. Observe that KG_{3,0} has 20 vertices and 10 edges. %o A342737 (Sage) [1+((n+1)*(n+3)*(n+4)*(n+6)/4) for n in range(50)] %K A342737 nonn,easy %O A342737 0,1 %A A342737 _Anurag Singh_, Mar 21 2021