cp's OEIS Frontend

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.

Showing 1-5 of 5 results.

A047759 Duplicate of A047772.

Original entry on oeis.org

0, 0, 0, 1, 8, 42, 232, 1277, 7183, 41041, 238315, 1402076, 8343804, 50136483
Offset: 0

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Keywords

A047758 Number of chiral pairs of dissectable polyhedra with n tetrahedral cells and symmetry of type G.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 8, 0, 0, 0, 42, 0, 0, 0, 232, 0, 0, 0, 1277, 0, 0, 0, 7183, 0, 0, 0, 41041, 0, 0, 0, 238315, 0, 0, 0, 1402076, 0, 0, 0, 8343804, 0, 0, 0, 50136483, 0, 0, 0, 303790544, 0, 0, 0, 1854115285, 0, 0, 0, 11388104153
Offset: 1

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Author

Keywords

Comments

One of 17 different symmetry types comprising A007173 and A027610 and one of 7 for A371350. Also the number of tetrahedral clusters or polyominoes of the regular tiling with Schläfli symbol {3,3,oo}, both having type G chiral symmetry and n tetrahedral cells. The axis of symmetry is a line connecting the centers of opposite edges of a tetrahedral cell (31); the order of the symmetry group is 4. Each member of a chiral pair is a reflection but not a rotation of the other. - Robert A. Russell, Mar 22 2024

Crossrefs

Cf. A047772.
Cf. A007173 (oriented), A027610 (unoriented), A371350 (chiral), A001764 (rooted), A047751 (type K), A047752 (type J), A047753 (type I).

Programs

  • Mathematica
    Table[If[1==Mod[n,4],(2Boole[1==n]+2Binomial[(3n-3)/4,(n-1)/4]/(n+1)-If[1==Mod[n,8],12Binomial[(3n-3)/8,(n-1)/8]/(n+3),12Binomial[(3n-7)/8,(n+3)/8]/(n-1)]-If[5==Mod[n,12],6Binomial[(n-5)/4,(n-5)/12]/(n+1)-If[5==Mod[n,24],36Binomial[(n-5)/8,(n-5)/12],72Binomial[(n-9)/8,(n-17)/24]]/(n+7),0])/6,0],{n,50}] (* Robert A. Russell, Mar 22 2024 *)

Formula

If n=4m+1 then (1/6)*(A001764(m) - 3*A047753(n) - 2*A047752(n) - A047751(n)), otherwise 0.
G.f.: z * (2 + G(z^4) - z^4*G(z^12) - 3 * (G(z^8) + z^4*G(z^8)^2 - z^4*G(z^24) - z^16*G(z^24)^2)) / 6, where G(z) = 1 + z*G(z)^3 is the g.f. for A001764. - Robert A. Russell, Mar 22 2024

A047771 Number of dissectable polyhedra with n tetrahedral cells and symmetry of type L.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 8, 0, 42, 0, 232, 0, 1277, 0, 7183, 0, 41041, 0, 238315, 0, 1402076, 0, 8343804, 0, 50136483, 0, 303790544, 0, 1854115285, 0, 11388104153, 0, 70338364135, 0, 436605050440, 0, 2722153369473, 0, 17040017600925, 0
Offset: 1

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Author

Keywords

Comments

One of 17 different symmetry types comprising A007173 and A027610 and one of 10 for A371351. Also the number of tetrahedral clusters or polyominoes of the regular tiling with Schläfli symbol {3,3,oo}, both having type L achiral symmetry and n tetrahedral cells. The plane of symmetry is a tetrahedral face (210); the order of the symmetry group is 2. An achiral polyomino is identical to its reflection. - Robert A. Russell, Mar 22 2024

Crossrefs

Cf. A047772.
Cf. A007173 (oriented), A027610 (unoriented), A371351 (achiral), A001764 (rooted), A047764 (type Q), A047765 (type P), A047766 (type N).

Programs

  • Mathematica
    Table[(If[OddQ[n],0,Binomial[3n/2,n/2]/(n+1)-6If[OddQ[n/2],2Binomial[(3n-2)/4,(n-2)/4],Binomial[3n/4,n/4]]/(n+2)]-3If[2==Mod[n,6],Binomial[3(n-2)/6,(n-2)/6]/(n+1)-If[2==Mod[n,12],6Binomial[3(n-2)/12,(n-2)/12],12Binomial[n/4-1,(n-8)/12]]/(n+4),0])/6,{n,30}] (* Robert A. Russell, Mar 22 2024 *)

Formula

If n=2m then (1/6)*(A001764(m) - 2*A047766(n) - 3*A047765(n) - A047764(n)), otherwise 0.
G.f.: (2 + G(z^2) - z^2*G(z^6)) / 6 - (G(z^4) + z^2*G(z^4)^2 - z^2*G(z^12) - z^8*G(z^12)^2) / 2, where G(z) = 1 + z*G(z)^3 is the g.f. for A001764. - Robert A. Russell, Mar 30 2024

A047775 Number of dissectable polyhedra with n tetrahedral cells and symmetry of type B.

Original entry on oeis.org

0, 0, 0, 0, 2, 5, 11, 25, 66, 131, 349, 708, 1911, 3856, 10604, 21597, 59961, 123266, 345060, 715198, 2015416, 4206926, 11919257, 25032840, 71246129, 150413234, 429750208, 911379241, 2612614298, 5562367173, 15991792731, 34164355260
Offset: 1

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Author

Keywords

Comments

One of 17 different symmetry types comprising A007173 and A027610 and one of 10 for A371351. Also the number of tetrahedral clusters or polyominoes of the regular tiling with Schläfli symbol {3,3,oo}, both having type B achiral symmetry and n tetrahedral cells. The plane of symmetry bisects a tetrahedral cell (321); the order of the symmetry group is 2. An achiral polyomino is identical to its reflection. - Robert A. Russell, Mar 29 2024

Crossrefs

Cf. A047772.
Cf. A007173 (oriented), A027610 (unoriented), A371351 (achiral), A001764 (rooted), A047749 (type U), A047751 (type K), A047753 (type I), A047760 (type F), A047764 (type Q), A047765 (type P), A047773 (type D).

Programs

Formula

a(n) = (1/2)*(A047749(n) - 2*A047773(n) - 2*A047760(n) - A047753(n) - A047751(n) - A047764(n) - A047765(n)).
G.f.: (2 - G(z^4) - G(z^6))/z + (G(z^2) + z*G(z^2)^2 - G(z^4) + z*G(z^4) - z^2*G(z^4)^2 + z^2*G(z^6) + z^2*G(z^12) + z^8*G(z^12)^2) / 2 + z - z*G(z^4)^2 - z*G(z^6) - z^2*G(z^6)^2 - z^4*G(z^6)^2 + z^5*G(z^24) + z^17*G(z^24)^2, where G(z) = 1 + z*G(z)^3 is the g.f. for A001764. - Robert A. Russell, Mar 29 2024

A121180 Alkane systems (see Cyvin reference for precise definition).

Original entry on oeis.org

0, 0, 0, 1, 1, 5, 6, 26, 32, 133, 176, 708, 952, 3861, 5302, 21604, 29960
Offset: 1

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Author

N. J. A. Sloane, Aug 17 2006

Keywords

Comments

Appears to be A047774 without every third term (all omitted terms are zeros). - Andrey Zabolotskiy, Jul 29 2023

Crossrefs

Cf. other columns of Cyvin et al.'s Table 5: A027610 (spectral isomers), A007173 (stereoisomers), A047775 (C_s), A047772 (C_i), A047774 (C_3, apparently), A047767 (C_{2h}), A047761 (C_{2v}), A047773 (C_{3v}, apparently).
Showing 1-5 of 5 results.