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.

Previous Showing 11-14 of 14 results.

A197989 Number of binary arrangements of total n 1's, without adjacent 1's on n X n array connected n-s.

Original entry on oeis.org

1, 4, 45, 886, 24395, 860336, 36914493, 1863645610, 108131503623, 7085585223652, 517329551346608, 41634263983867842, 3661077644199252550, 349191617521920855488, 35902782820742394839453, 3958207187579046500083794, 465777357329812920074875295
Offset: 1

Views

Author

Vaclav Kotesovec, Oct 20 2011

Keywords

Crossrefs

Programs

  • Mathematica
    permopak[part_,k_]:=(hist=ConstantArray[0,k];
    Do[hist[[part[[t]]]]++,{t,1,Length[part]}];
    (Length[part])!/Product[(hist[[t]])!,{t,1,k}]);
    waz1n[k_,n_]:=(If[n-k+1
    				

Formula

Asymptotic (V. Kotesovec, Oct 15 2011): a(n) ~ n^(2n)/n!*exp(-3/2).

A210343 a(n) = Fibonacci(n+1)^n.

Original entry on oeis.org

1, 1, 4, 27, 625, 32768, 4826809, 1801088541, 1785793904896, 4605366583984375, 31181719929966183601, 552061438912436417593344, 25601832525455335435322705761, 3107689015140868348741078056241817, 987683253336131809511244100000000000000
Offset: 0

Views

Author

Emanuele Munarini, Mar 20 2012

Keywords

Crossrefs

Programs

  • Magma
    [Fibonacci(n+1)^n: n in [0..14]]; // Bruno Berselli, Mar 28 2012
  • Maple
    a:= n-> (<<1|1>, <1|0>>^n)[1,1]^n:
    seq(a(n), n=0..15);  # Alois P. Heinz, Dec 05 2015
  • Mathematica
    Table[Fibonacci[n+1]^n,{n,0,100}]
  • Maxima
    makelist(fib(n+1)^n,n,0,14);
    

A182562 Number of ways to place k non-attacking semi-knights on an n x n chessboard, sum over all k>=0.

Original entry on oeis.org

2, 16, 288, 11664, 1458000, 506250000, 414720000000, 869730877440000, 5045702916833280000, 77297454895962562560000, 3017525202366485003182080000, 307389127582207654481154908160000, 83016370640108703579427655610531840000, 58770343311359208383258439665073059266560000
Offset: 1

Views

Author

Vaclav Kotesovec, May 05 2012

Keywords

Comments

Semi-knight is a semi-leaper [1,2]. Moves of a semi-knight are allowed only in [2,1] and [-2,-1]. See also semi-bishops (A187235).

Crossrefs

Programs

  • Mathematica
    Table[If[EvenQ[n],Fibonacci[n/2+2]^(n+2)*Product[Fibonacci[j+2]^4,{j,1,n/2-1}],Fibonacci[(n+1)/2+2]^((n+1)/2)*Fibonacci[(n-1)/2+2]^((n-1)/2)*Product[Fibonacci[j+2]^4,{j,1,(n-1)/2}]],{n,1,20}]

Formula

a(n) = F(n/2+2)^(n+2)*prod(j=1,n/2-1,F(j+2)^4) if n is even, F((n+1)/2+2)^((n+1)/2)*F((n-1)/2+2)^((n-1)/2)*prod(j=1,(n-1)/2,F(j+2)^4) if n is odd, where F(n) = A000045(n) is the n-th Fibonacci number.
a(n) is asymptotic to C^4*((1+sqrt(5))/2)^((n+2)*(n+4))/5^(3/2*(n+2)), where C=1.226742010720353244... is Fibonacci Factorial Constant, see A062073.

A201222 Number of ways to place k non-attacking knights on a 2 X n horizontal cylinder, summed over all k>=0.

Original entry on oeis.org

3, 9, 18, 81, 123, 324, 843, 2401, 5778, 15129, 39603, 104976, 271443, 710649, 1860498, 4879681, 12752043, 33385284, 87403803, 228886641, 599074578, 1568397609, 4106118243, 10750371856, 28143753123, 73681302249, 192900153618, 505022001201, 1322157322203
Offset: 1

Views

Author

Vaclav Kotesovec, Nov 28 2011

Keywords

Crossrefs

Programs

  • Mathematica
    Table[If[Mod[n,4]==0,LucasL[n/2]^4,LucasL[2n]+1+(-1)^n],{n,1,50}]
Previous Showing 11-14 of 14 results.