A063675 Erroneous version of A000943.
1, 2, 5, 8, 18, 29, 57, 96, 183, 318, 603, 1080, 2047, 3762
Offset: 1
Keywords
References
- B. Grünbaum, Convex Polytopes. Wiley, NY, 1967, p. 424.
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.
a(2) = -1 because of the regular polygons in the plane. a(3) = 5 because in R^3 the regular convex polytopes are the 5 Platonic solids.
PadRight[{1, 1, -1, 5, 6}, 100, 3] (* Paolo Xausa, Jan 29 2025 *)
N:=60: with(numtheory): G:=-ln(1-2*x^3/(1-2*x)^2): H:=-ln(1-2*x)+ln(1-x): K:=-1/2*x*(x-8*x^3-1+5*x^2-7*x^4+2*x^6+5*x^8-9*x^7+19*x^5-14*x^9+x^10+19*x^11-5*x^12+4*x^14-8*x^13)/(1-x)^5/(2*x^6-4*x^4+4*x^2-1)/(x+1)^2: series(1/(x^3-x^4)*(1/4*sum(phi(2*r+1)/(2*r+1)*subs(x=x^(2*r+1),G),r=0..N)+1/2*sum(phi(r)/r*subs(x=x^r,H),r=1..N)+K),x,N);
terms = 26;
G[x_] = -Log[1 - 2(x^3/(1 - 2x)^2)];
H[x_] = -Log[1 - 2x] + Log[1 - x];
K[x_] = -1/2 x (x - 8x^3 - 1 + 5x^2 - 7x^4 + 2x^6 + 5x^8 - 9x^7 + 19x^5 - 14x^9 + x^10 + 19x^11 - 5x^12 + 4x^14 - 8x^13)/(1-x)^5/(2x^6 - 4x^4 + 4x^2 - 1)/(x+1)^2;
1/(x^3 - x^4) (1/4 Sum[EulerPhi[2r + 1]/(2r + 1) G[x^(2r + 1)], {r, 0, terms+2}] + 1/2 Sum[EulerPhi[r]/r H[x^r], {r, 1, terms+2}] + K[x]) + O[x]^(terms+2) // CoefficientList[#, x]& // Rest // Most // Round (* Jean-François Alcover, Dec 14 2018 *)
N:=30: with(numtheory): G:=-ln(1-2*x^3/(1-2*x)^2): H:=-log(1-2*x)+ln(1-x): K:=-(x^10+3*x^9-3*x^8-7*x^7+4*x^6+4*x^5+4*x^4+3*x^3-2*x^2+1)*x/(1-x)^5/(x+1)^3: series(1/(x^3-x^4)*(1/2*sum(phi(2*r+1)/(2*r+1)*subs(x=x^(2*r+1),G),r=0..N)+sum(phi(r)/r*subs(x=x^r,H),r=1..N)+K),x,N);
terms = 26;
G[x_] = -Log[1 - 2 (x^3/(1 - 2 x)^2)];
H[x_] = -Log[1 - 2 x] + Log[1 - x];
K[x_] = -(x^10 + 3 x^9 - 3 x^8 - 7 x^7 + 4 x^6 + 4 x^5 + 4 x^4 + 3 x^3 - 2 x^2 + 1) x/(1 - x)^5/(x + 1)^3;
1/(x^3 - x^4) (1/2 Sum[EulerPhi[2 r + 1]/(2 r + 1) G[x^(2 r + 1)], {r, 0, terms+3}] + Sum[EulerPhi[r]/r H[x^r], {r, 1, terms+3}] + K[x]) + O[x]^(terms+2) // CoefficientList[#, x]& // Rest // Most // Round (* Jean-François Alcover, Dec 14 2018 *)
LinearRecurrence[{2, 6, -14, -12, 38, 8, -54, 5, 44, -12, -20, 8, 4, -2}, {0, 1, 7, 24, 62, 141, 287, 561, 1035, 1886, 3319, 5838, 10030, 17323}, 32] (* Jean-François Alcover, Dec 14 2018 *)
concat(0, Vec((2*x^11+4*x^10-2*x^9-15*x^8-5*x^7+23*x^6+15*x^5 -17*x^4-14*x^3+4*x^2 +5*x+1)*x^2/ (-1+x)^5/(2*x^6-4*x^4+4*x^2-1)/(x+1)^3 + O(x^50))) \\ Michel Marcus, Dec 12 2014
a(0) = 1 because the 0-D regular polytope is the point. a(1) = 2 because the only regular 1-D polytope is the line segment, with 2 vertices, one at each end. a(2) = 0, indicating infinity, because the regular k-gon has k vertices. a(3) = 50 (4 for the tetrahedron, 6 for the octahedron, 8 for the cube, 12 for the icosahedron, 20 for the dodecahedron) = the sum of A053016. a(4) = 773 = 5 + 8 + 16 + 24 + 120 + 600 = sum of A063924. For n>4 there are only the three regular n-dimensional polytopes, the simplex with n+1 vertices, the hypercube with 2^n vertices and the hyperoctahedron = cross polytope = orthoplex with 2*n vertices, for a total of A086653(n) + 1 = 2^n + 3*n + 1 (again restricted to n > 4).
LinearRecurrence[{4, -5, 2}, {1, 2, 0, 50, 773, 48, 83, 150}, 32] (* Georg Fischer, May 03 2019 *)
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