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 1-4 of 4 results.

A324490 A324487(3*n).

Original entry on oeis.org

0, 64, 4096, 438976, 32768000, 2537716544, 192699928576, 14662949322176, 1114512556032000, 84722519068761664, 6440005257691303936, 489526700523945017536, 37210462578386173952000, 2828485190904971429628224
Offset: 0

Views

Author

N. J. A. Sloane, Mar 12 2019

Keywords

Crossrefs

A152152 a(n) = Product_{k=1..n} (1 + 4*sin(2*Pi*k/n)^2).

Original entry on oeis.org

0, 1, 1, 16, 25, 121, 256, 841, 2025, 5776, 14641, 39601, 102400, 271441, 707281, 1860496, 4862025, 12752041, 33362176, 87403801, 228765625, 599074576, 1568239201, 4106118241, 10749542400, 28143753121, 73680216481, 192900153616
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Nov 26 2008

Keywords

Crossrefs

Programs

  • Magma
    [(1-Lucas(n)+(-1)^n)^2: n in [0..30]]; // G. C. Greubel, Mar 13 2019
    
  • Mathematica
    Table[(1 + Fibonacci[n] - 2*Fibonacci[n+1] + (-1)^n)^2, {n, 0, 30}]
  • PARI
    {a(n) = (1-fibonacci(n-1)-fibonacci(n+1)+(-1)^n)^2}; \\ G. C. Greubel, Mar 13 2019
    
  • Sage
    [(1-lucas_number2(n,1,-1)+(-1)^n)^2 for n in (0..30)] # G. C. Greubel, Mar 13 2019

Formula

a(n) = Product_{k=1..n} (1 + 4*sin(2*Pi*k/n)^2).
a(n) = (1 + Fibonacci(n) - 2*Fibonacci(n + 1) + (-1)^n)^2.
G.f.: -x*(x^6 -2*x^5 +10*x^4 -14*x^3 +10*x^2 -2*x +1)/((x -1)*(x +1)*(x^2 -3*x +1)*(x^2 -x -1)*(x^2 +x -1)). - Colin Barker, Apr 13 2014
a(n) = A001350(n)^2. - Colin Barker, Apr 13 2014
a(n) = (1 + (-1)^n - Lucas(n))^2. - G. C. Greubel, Mar 13 2019

A324489 a(n) = A324488(n)/n.

Original entry on oeis.org

1, 0, 21, 31, 266, 672, 3484, 11375, 48768, 177023, 716418, 2730315, 10878520, 42485638, 169181010, 670042125, 2678678730, 10705526976, 43007270292, 173003915322, 698235680844, 2822901487191, 11439823946306, 46438021798875, 188856966693230, 769224288476860, 3137871076604544, 12817404260955810
Offset: 1

Views

Author

N. J. A. Sloane, Mar 12 2019

Keywords

Crossrefs

Programs

  • PARI
    a001350(n) = fibonacci(n+1)+fibonacci(n-1)-1-(-1)^n;
    a(n) = sumdiv(n, d, moebius(n/d)*a001350(d)^3)/n; \\ Seiichi Manyama, Apr 29 2021
    
  • PARI
    f(x) = ((1-3*x+x^2)*(1+3*x+x^2))^3*(1-x^2)^10/((1-4*x-x^2)*(1-x-x^2)^6*(1+x-x^2)^9);
    my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, moebius(k)*log(f(x^k))/k)) \\ Seiichi Manyama, Apr 29 2021

Formula

From Seiichi Manyama, Apr 29 2021: (Start)
a(n) = (1/n) * Sum_{d|n} mu(n/d) * A001350(d)^3 = (1/n) * Sum_{d|n} mu(n/d) * A324487(d).
G.f.: Sum_{k>=1} mu(k) * log(f(x^k))/k , where f(x) = ((1-3*x+x^2) * (1+3*x+x^2))^3 * (1-x^2)^10/((1-4*x-x^2) * (1-x-x^2)^6 * (1+x-x^2)^9). (End)

Extensions

More terms from Seiichi Manyama, Apr 29 2021

A324488 Inflation orbit counts b^{(3)}_n for Danzer's F-type tiling and other 3D cut and project patterns with tau-inflation.

Original entry on oeis.org

1, 0, 63, 124, 1330, 4032, 24388, 91000, 438912, 1770230, 7880598, 32763780, 141420760, 594798932, 2537715150, 10720674000, 45537538410, 192699485568, 817138135548, 3460078306440, 14662949297724, 62103832718202, 263115950765038, 1114512523173000, 4721424167330750
Offset: 1

Views

Author

N. J. A. Sloane, Mar 12 2019

Keywords

Crossrefs

Programs

  • PARI
    a001350(n) = fibonacci(n+1)+fibonacci(n-1)-1-(-1)^n;
    a(n) = sumdiv(n, d, moebius(n/d)*a001350(d)^3); \\ Seiichi Manyama, Apr 29 2021

Formula

a(n) = Sum_{d|n} mu(n/d) * A001350(d)^3 = Sum_{d|n} mu(n/d) * A324487(d). - Seiichi Manyama, Apr 29 2021

Extensions

More terms from Seiichi Manyama, Apr 29 2021
Showing 1-4 of 4 results.