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.

A077071 Row sums of A077070.

Original entry on oeis.org

0, 2, 8, 16, 30, 46, 66, 88, 118, 150, 186, 224, 268, 314, 364, 416, 478, 542, 610, 680, 756, 834, 916, 1000, 1092, 1186, 1284, 1384, 1490, 1598, 1710, 1824, 1950, 2078, 2210, 2344, 2484, 2626, 2772, 2920, 3076, 3234, 3396, 3560, 3730, 3902, 4078, 4256
Offset: 0

Views

Author

Michael Somos, Oct 25 2002

Keywords

Comments

Conjecture: given n balls, all of which are initially in the first of n numbered boxes, a(n-1) is the number of steps of the following process required to move them all to the last box. A step consists of first identifying j, the lowest numbered box which has at least one ball. If it has only one ball then move it to box j+1; otherwise move half its balls rounded down to box j+1 and (unless it's the first box) half its balls rounded down to box j-1. See also A356254. - Mikhail Kurkov, Nov 24 2022

Crossrefs

Programs

  • PARI
    {a(n) = sum( k=0, n, -valuation( polcoeff( pollegendre(2*n), 2*k), 2))}
    
  • PARI
    a(n)=my(P=pollegendre(2*n)); -sum(k=0,n,valuation(polcoeff(P,2*k), 2)) \\ Charles R Greathouse IV, Apr 12 2012
    
  • Python
    def A077071(n): return ((n+1)*(n-n.bit_count())<<1)-sum((m:=1<>j)-(r if n<<1>=m*(r:=k<<1|1) else 0)) for j in range(1,n.bit_length()+1)) # Chai Wah Wu, Nov 12 2024

Formula

a(n) is asymptotic to 2*n^2 and it seems that a(n) = 2*n^2 + O(n^(3/2)) (where O(n^(3/2))/n^(3/2) is bounded and O(n^(3/2)) < 0). - Benoit Cloitre, Oct 30 2002
G.f.: (1/(1-x)^2) * Sum_{k>=0} t/(1-t) where t = x^2^k. Twice the value of the partial sum of A005187. a(0) = 0, a(2n) = a(n) + a(n-1) + 4*n^2 + 2*n, a(2n+1) = 2*a(n) + 4*n^2 + 6*n + 2. - Ralf Stephan, Sep 12 2003
a(n) = 2*n*(n+1) - 2*A000788(n) and therefore asymptotically a(n) = 2*n^2 - n*log_2(n) + O(n). - Peter J. Taylor, Dec 21 2022

A144816 Denominators of triangle T(n,k), n>=0, 0<=k<=n, read by rows: T(n,k) is the coefficient of x^(2*k+1) in polynomial t_n(x), used to define continuous and n times differentiable sigmoidal transfer functions.

Original entry on oeis.org

1, 2, 2, 8, 4, 8, 16, 16, 16, 16, 128, 32, 64, 32, 128, 256, 256, 128, 128, 256, 256, 1024, 512, 1024, 256, 1024, 512, 1024, 2048, 2048, 2048, 2048, 2048, 2048, 2048, 2048, 32768, 4096, 8192, 4096, 16384, 4096, 8192, 4096, 32768, 65536, 65536, 16384, 16384, 32768, 32768, 16384, 16384, 65536, 65536
Offset: 0

Views

Author

Alois P. Heinz, Sep 21 2008

Keywords

Examples

			Triangle begins:
    1;
    2,  2;
    8,  4,  8;
   16, 16, 16, 16;
  128, 32, 64, 32, 128;
  ...
		

Crossrefs

See A144815 for more information on T(n,k).
Main diagonal and column k=0 gives A046161.
Column k=1 gives A101926(n-1) = 2^A101925(n-1) = 2^(A005187(n-1)+1).
Cf. A077070.

Programs

  • Maple
    # Function T(n,k) defined in A144815.
    seq(seq(denom(T(n,k)), k=0..n), n=0..10);
  • Mathematica
    row[n_] := Module[{f, a, eq}, f = Function[x, Sum[a[2*k+1]*x^(2*k+1), {k, 0, n}]]; eq = Table[Derivative[k][f][1] == If[k == 0, 1, 0], {k, 0, n}]; Table[a[2*k+1], {k, 0, n}] /. Solve[eq] // First]; Table[row[n] // Denominator, {n, 0, 10}] // Flatten (* Jean-François Alcover, Feb 03 2014 *)

A076178 a(n) = 2*n^2 - A077071(n).

Original entry on oeis.org

0, 0, 0, 2, 2, 4, 6, 10, 10, 12, 14, 18, 20, 24, 28, 34, 34, 36, 38, 42, 44, 48, 52, 58, 60, 64, 68, 74, 78, 84, 90, 98, 98, 100, 102, 106, 108, 112, 116, 122, 124, 128, 132, 138, 142, 148, 154, 162, 164, 168, 172, 178, 182, 188, 194, 202, 206, 212, 218, 226, 232
Offset: 0

Views

Author

Benoit Cloitre, Nov 01 2002

Keywords

Crossrefs

Equals 2 * A078903(n).

Programs

  • PARI
    a(n)=2*n^2-sum(k=0,n,-valuation(polcoeff(pollegendre(2*n),2*k),2))
    
  • Python
    def A076178(n): return ((n+1)*n.bit_count()-n<<1)+sum((m:=1<>j)-(r if n<<1>=m*(r:=k<<1|1) else 0)) for j in range(1,n.bit_length()+1)) # Chai Wah Wu, Nov 12 2024

Formula

a(n) = A001105(n) - A077071(n). - Omar E. Pol, Nov 13 2024
Showing 1-3 of 3 results.