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.

A028294 a(n) = n^5 - (65/6)*n^4 + (173/6)*n^3 + (148/3)*n^2 - (862/3)*n + 265.

Original entry on oeis.org

1, 20, 281, 1357, 4281, 10666, 22825, 43891, 77937, 130096, 206681, 315305, 465001, 666342, 931561, 1274671, 1711585, 2260236, 2940697, 3775301, 4788761, 6008290, 7463721, 9187627, 11215441, 13585576, 16339545, 19522081, 23181257, 27368606, 32139241
Offset: 4

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Comments

Old name was: "Number of stacks of n pikelets, distance 5 flips from a well-ordered stack".

Programs

  • Magma
    [n^5 - (65/6)*n^4 + (173/6)*n^3 + (148/3)*n^2 - (862/3)*n + 265 : n in [4..40]]; // Wesley Ivan Hurt, Aug 28 2015
    
  • Magma
    I:=[1,20,281,1357,4281,10666]; [n le 6 select I[n] else 6*Self(n-1)-15*Self(n-2)+20*Self(n-3)-15*Self(n-4)+6*Self(n-5)-Self(n-6): n in [1..40]]; // Vincenzo Librandi, Aug 29 2015
    
  • Maple
    A028294:=n->n^5 - (65/6)*n^4 + (173/6)*n^3 + (148/3)*n^2 - (862/3)*n + 265: seq(A028294(n), n=4..40); # Wesley Ivan Hurt, Aug 28 2015
  • Mathematica
    CoefficientList[Series[(9*x^5 - 31*x^4 - 49*x^3 + 176*x^2 + 14*x + 1)/(x - 1)^6, {x, 0, 40}], x] (* Wesley Ivan Hurt, Aug 28 2015 *)
    Table[n^5 - (65/6) n^4 + (173/6) n^3 + (148/3) n^2 - (862/3)n + 265, {n, 4, 40}] (* Vincenzo Librandi, Aug 29 2015 *)
    LinearRecurrence[{6,-15,20,-15,6,-1},{1,20,281,1357,4281,10666},40] (* Harvey P. Dale, Dec 29 2018 *)
  • PARI
    Vec(x^4*(9*x^5-31*x^4-49*x^3+176*x^2+14*x+1)/(x-1)^6 + O(x^100)) \\ Colin Barker, Jun 04 2014
    
  • SageMath
    [(6*n^5 -65*n^4 +173*n^3 +296*n^2 -1724*n +1590)/6 for n in range(4,41)] # G. C. Greubel, Jan 03 2024

Formula

G.f.: x^4*(1+14*x+176*x^2-49*x^3-31*x^4+9*x^5) / (1-x)^6. - Colin Barker, Jun 04 2014
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6). - Wesley Ivan Hurt, Aug 28 2015
E.g.f.: (x^5 -(5/6)*x^4 - (67/6)*x^3 + 75*x^2 - 219*x + 265)*exp(x) + (3/2)*x^3 + (23/2)*x^2 - 46*x - 265. - G. C. Greubel, Aug 29 2015

Extensions

More terms from David Wasserman, Jan 22 2005
Entry revised by N. J. A. Sloane, Jun 15 2014