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 1-3 of 3 results.

A016743 Even cubes: a(n) = (2*n)^3.

Original entry on oeis.org

0, 8, 64, 216, 512, 1000, 1728, 2744, 4096, 5832, 8000, 10648, 13824, 17576, 21952, 27000, 32768, 39304, 46656, 54872, 64000, 74088, 85184, 97336, 110592, 125000, 140608, 157464, 175616, 195112, 216000, 238328, 262144, 287496, 314432
Offset: 0

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Comments

a(n) is also the number of non-degenerate triangles that can be drawn with vertices on a cross with n points on each branch. - James P. B. Hall, Nov 22 2019

Crossrefs

Even bisection of A000578, cf. A016755.
Cf. A016803 (even bisection), A016827 (odd bisection), A033581, A276712.

Programs

Formula

a(n) = (2*n)^3 = 8*n^3.
G.f.: x*(8+32*x+8*x^2)/(1-4*x+6*x^2-4*x^3+x^4). - Colin Barker, Jan 02 2012
E.g.f.: 8*x*(1 +3*x +x^2)*exp(x). - G. C. Greubel, Sep 15 2018
From Amiram Eldar, Oct 10 2020: (Start)
Sum_{n>=1} 1/a(n) = zeta(3)/8 (A276712).
Sum_{n>=1} (-1)^(n+1)/a(n) = 3*zeta(3)/32. (End)

A016830 a(n) = (4*n+2)^6.

Original entry on oeis.org

64, 46656, 1000000, 7529536, 34012224, 113379904, 308915776, 729000000, 1544804416, 3010936384, 5489031744, 9474296896, 15625000000, 24794911296, 38068692544, 56800235584, 82653950016, 117649000000, 164206490176, 225199600704, 304006671424, 404567235136, 531441000000
Offset: 0

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Crossrefs

Programs

  • Mathematica
    (4*Range[0,20]+2)^6 (* or *) LinearRecurrence[{7,-21,35,-35,21,-7,1},{64,46656,1000000,7529536,34012224,113379904,308915776},20] (* Harvey P. Dale, Oct 14 2012 *)

Formula

a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7). - Harvey P. Dale, Oct 14 2012
From Amiram Eldar, Jul 07 2022: (Start)
a(n) = A016825(n)^6 = A016826(n)^3 = A016827(n)^2 = 64*A016758(n).
Sum_{n>=0} 1/a(n) = Pi^6/61440. (End)

A017115 a(n) = (8*n + 4)^3.

Original entry on oeis.org

64, 1728, 8000, 21952, 46656, 85184, 140608, 216000, 314432, 438976, 592704, 778688, 1000000, 1259712, 1560896, 1906624, 2299968, 2744000, 3241792, 3796416, 4410944, 5088448, 5832000, 6644672, 7529536, 8489664, 9528128, 10648000, 11852352, 13144256, 14526784, 16003008
Offset: 0

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Crossrefs

Programs

  • Magma
    [(8*n+4)^3: n in [0..35] ]; // Vincenzo Librandi, Jul 21 2011
  • Mathematica
    LinearRecurrence[{4, -6, 4, -1},{64, 1728, 8000, 21952},24] (* Ray Chandler, Aug 04 2015 *)

Formula

G.f.: 64*(1+x)*(x^2 + 22*x + 1)/(x-1)^4. - R. J. Mathar, Jul 14 2016
From Amiram Eldar, Apr 25 2023: (Start)
a(n) = A017113(n)^3.
a(n) = 2^3*A016827(n) = 2^6*A016755(n).
Sum_{n>=0} 1/a(n) = 7*zeta(3)/512.
Sum_{n>=0} (-1)^n/a(n) = Pi^3/2048. (End)
E.g.f.: 64*exp(x)*(1 + 26*x + 36*x^2 + 8*x^3). - Stefano Spezia, May 27 2025
Showing 1-3 of 3 results.