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.

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A193390 The hyper-Wiener index of a benzenoid consisting of a straight-line chain of n hexagons (s=2; see the Gutman et al. reference).

Original entry on oeis.org

42, 215, 680, 1661, 3446, 6387, 10900, 17465, 26626, 38991, 55232, 76085, 102350, 134891, 174636, 222577, 279770, 347335, 426456, 518381, 624422, 745955, 884420, 1041321, 1218226, 1416767, 1638640, 1885605, 2159486, 2462171, 2795612, 3161825, 3562890, 4000951, 4478216
Offset: 1

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Author

Emeric Deutsch, Jul 25 2011

Keywords

Crossrefs

Programs

  • Magma
    [(8*n^4 + 32*n^3 + 46*n^2 + 37*n + 3)/3: n in [1..30]]; // Vincenzo Librandi, Jul 26 2011
    
  • Maple
    a := proc (n) options operator, arrow: (8/3)*n^4+(32/3)*n^3+(46/3)*n^2+(37/3)*n+1 end proc; seq(a(n), n = 1 .. 35);
  • PARI
    a(n)=(8*n^4+32*n^3+46*n^2+37*n)/3+1 \\ Charles R Greathouse IV, Jul 26 2011

Formula

a(n) = (8*n^4 + 32*n^3 + 46*n^2 + 37*n + 3)/3.
The Wiener-Hosoya polynomial is W(n,t) = (2*(t+1)*t^(2*n+2) - t^3 - 2*t^2 - 3*t + n*(t-1)*(t^2+1)*(t^2-t-4)+2)/(1-t)^2.
G.f.: x*(42 + 5*x + 25*x^2 - 9*x^3 + x^4)/(1-x)^5. - Bruno Berselli, Jul 27 2011

A193400 Hyper-Wiener index of a benzenoid consisting of a chain of n hexagons characterized by the encoding s = 1133 (see the Gutman et al. reference, Sec. 5).

Original entry on oeis.org

42, 215, 636, 1513, 2862, 5211, 8352, 13229, 19314, 28063, 38532, 52785, 69366, 91043, 115752, 147061, 182202, 225639, 273804, 332153, 396222, 472555, 555696, 653373, 759042, 881711, 1013652, 1165249, 1327494, 1512243, 1709112, 1931525, 2167626, 2432503, 2712732
Offset: 1

Views

Author

Emeric Deutsch, Jul 25 2011

Keywords

Crossrefs

Programs

  • Magma
    [(6*n^4 + 40*n^3 + 114*n^2 + 16*n - 45 + (-1)^n*(6*n^2 +20*n -63))/4: n in [1..40]]; // Vincenzo Librandi, Jul 26 2011
    
  • Maple
    a := proc (n) options operator, arrow: (3/2)*n^4+10*n^3+(57/2)*n^2+4*n-45/4+(1/4)*(-1)^n*(6*n^2+20*n-63) end proc: seq(a(n), n = 1 .. 35);
  • PARI
    a(n)=(6*n^4+40*n^3+114*n^2+16*n-45+(-1)^n*(6*n^2+20*n-63))/4 \\ Charles R Greathouse IV, Jul 28 2011

Formula

a(n) = ( 6*n^4 +40*n^3 +114*n^2 +16*n -45 +(-1)^n*(6*n^2 +20*n -63) )/4.
G.f.: x*(42+131*x+122*x^2+63*x^3-146*x^4+25*x^5+78*x^6-27*x^7)/((1+x)^3*(1-x)^5). - Bruno Berselli, Jul 27 2011

A228597 The Wiener index of the graph obtained by applying Mycielski's construction to a benzenoid consisting of a linear chain of n hexagons.

Original entry on oeis.org

141, 445, 941, 1629, 2509, 3581, 4845, 6301, 7949, 9789, 11821, 14045, 16461, 19069, 21869, 24861, 28045, 31421, 34989, 38749, 42701, 46845, 51181, 55709, 60429, 65341, 70445, 75741, 81229, 86909, 92781, 98845, 105101, 111549, 118189
Offset: 1

Views

Author

Emeric Deutsch, Aug 27 2013

Keywords

References

  • D. B. West, Introduction to Graph Theory, 2nd ed., Prentice-Hall, NJ, 2001, p. 205.

Crossrefs

Cf. A143937.

Programs

  • Magma
    [96*n^2+16*n+29: n in [1..40]]; // Vincenzo Librandi, Dec 09 2016
  • Maple
    a := proc (n) options operator, arrow: 96*n^2+16*n+29 end proc: seq(a(n), n = 1 .. 35);
  • Mathematica
    LinearRecurrence[{3, -3, 1}, {141, 445, 941}, 100] (* or *) Table[96*n^2 + 16*n + 29 , {n,1,100}] (* G. C. Greubel, Dec 08 2016 *)
  • PARI
    Vec(x*(141+22*x+29*x^2)/(1-x)^3 + O(x^50)) \\ G. C. Greubel, Dec 08 2016
    

Formula

a(n) = 96*n^2 + 16*n + 29.
G.f.: x*(141+22*x+29*x^2)/(1-x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - G. C. Greubel, Dec 08 2016
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