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.

A181322 Square array A(n,k), n>=0, k>=0, read by antidiagonals: A(n,k) is the number of partitions of 2*n into powers of 2 less than or equal to 2^k.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 4, 4, 1, 1, 2, 4, 6, 5, 1, 1, 2, 4, 6, 9, 6, 1, 1, 2, 4, 6, 10, 12, 7, 1, 1, 2, 4, 6, 10, 14, 16, 8, 1, 1, 2, 4, 6, 10, 14, 20, 20, 9, 1, 1, 2, 4, 6, 10, 14, 20, 26, 25, 10, 1, 1, 2, 4, 6, 10, 14, 20, 26, 35, 30, 11, 1, 1, 2, 4, 6, 10, 14, 20, 26, 36, 44, 36, 12, 1, 1, 2, 4, 6, 10, 14, 20, 26, 36, 46, 56, 42, 13, 1
Offset: 0

Views

Author

Alois P. Heinz, Jan 26 2011

Keywords

Comments

Column sequences converge towards A000123.

Examples

			A(3,2) = 6, because there are 6 partitions of 2*3=6 into powers of 2 less than or equal to 2^2=4: [4,2], [4,1,1], [2,2,2], [2,2,1,1], [2,1,1,1,1], [1,1,1,1,1,1].
Square array A(n,k) begins:
  1,  1,  1,  1,  1,  1,  ...
  1,  2,  2,  2,  2,  2,  ...
  1,  3,  4,  4,  4,  4,  ...
  1,  4,  6,  6,  6,  6,  ...
  1,  5,  9, 10, 10, 10,  ...
  1,  6, 12, 14, 14, 14,  ...
		

Crossrefs

Columns k=0-5 give: A000012, A000027(n+1), A002620(n+2), A008804, A088932, A088954.
Main diagonal gives A000123.
Cf. A145515.
See A262553 for another version of this array.
See A072170 for a related array (having the same limiting column).

Programs

  • Maple
    b:= proc(n, j) local nn, r;
          if n<0 then 0
        elif j=0 then 1
        elif j=1 then n+1
        elif n b(n/2^(k-1), k):
    seq(seq(A(n, d-n), n=0..d), d=0..13);
  • Mathematica
    b[n_, j_] := b[n, j] = Module[{nn, r}, Which[n<0, 0, j == 0, 1, j == 1, n+1, nJean-François Alcover, Jan 15 2014, translated from Maple *)
  • PARI
    A181322(n,k,r=1)={if(nA181322(n-1,k,0)+A181322(2*n,k-1,0),n-=r=1+n\1,(r-k)*binomial(r,k)*sum(i=0,min(k-1,k+n), binomial(k,i)/(r-k+i)*A181322(k-i+n,k,0) *(-1)^i))} \\ From Maple. - M. F. Hasler, Feb 19 2019

Formula

G.f. of column k: 1/(1-x) * 1/Product_{j=0..k-1} (1 - x^(2^j)).
A(n,k) = Sum_{i=0..k} A089177(n,i).
For n < 2^k, T(n,k) = A000123(k). T(n,0) = 1, T(n,1) = n+1. - M. F. Hasler, Feb 19 2019

A088932 G.f.: 1/((1-x)^2*(1-x^2)*(1-x^4)*(1-x^8)).

Original entry on oeis.org

1, 2, 4, 6, 10, 14, 20, 26, 36, 46, 60, 74, 94, 114, 140, 166, 201, 236, 280, 324, 380, 436, 504, 572, 656, 740, 840, 940, 1060, 1180, 1320, 1460, 1625, 1790, 1980, 2170, 2390, 2610, 2860, 3110, 3396, 3682, 4004, 4326, 4690, 5054, 5460, 5866, 6321, 6776, 7280, 7784
Offset: 0

Views

Author

N. J. A. Sloane, Dec 02 2003

Keywords

Comments

a(n) is the number of partitions of 2*n into powers of 2 less than or equal to 2^4. First differs from A000123 at n=16. - Alois P. Heinz, Apr 02 2012

Crossrefs

See A000027, A002620, A008804, A088954, A000123 for similar sequences.
Column k=4 of A181322.
Cf. A010873.

Programs

  • Maple
    f := proc(n,k) option remember; if k > n then RETURN(0); fi; if k= 0 then if n=0 then RETURN(1) else RETURN(0); fi; fi; if k = 1 then RETURN(1); fi; if n mod 2 = 1 then RETURN(f(n-1,k)); fi; f(n-1,k)+f(n/2,k-1); end; # present sequence is f(2m,5)
    GFF := k->x^(2^(k-2))/((1-x)*mul((1-x^(2^j)),j=0..k-2)); # present g.f. is GFF(5)/x^8
    a:= proc(n) local m, r; m := iquo(n, 8, 'r'); r:= r+1; [1, 2, 4, 6, 10, 14, 20, 26][r]+ (((8/3*m +(4*r +28)/3)*m +[0, 4, 9, 14, 20, 26, 33, 40][r] +43/3)*m +[22, 33, 50, 67, 93, 119, 154, 189][r]/3)*m end: seq(a(n), n=0..60); # Alois P. Heinz, Apr 17 2009
  • Mathematica
    CoefficientList[Series[1/((1-x)^2(1-x^2)(1-x^4)(1-x^8)), {x,0,60}], x]  (* Harvey P. Dale, Apr 22 2011 *)
    Table[1 + 1237*n/1536 + 17*n^2/96 + 13*n^3/768 + n^4/1536 + (5/32 + n/32) * Floor[n/4] + (81/256 + 3*n/32 + n^2/128) * Floor[n/2] - Floor[(n+1)/8]/4 - (n+3) * Floor[(n+1)/4]/32 - Floor[(n+2)/8]/4, {n, 0, 100}] (* Vaclav Kotesovec, May 02 2018 *)
    Table[Simplify[1023/1024 + 85*n/96 + 341*n^2/1536 + n^3/48 + n^4/1536 + (-1)^n*(113/1024 + n/32 + n^2/512) - (1 + Sqrt[2])*Cos[Pi*n/4]/16 + Cos[Pi*n/2]/64 + (Sqrt[2] - 1) * Cos[3*Pi*n/4]/16 + (1/8 + n/64)*Sin[Pi*n/2]], {n, 0, 100}] (* Vaclav Kotesovec, May 02 2018 *)
  • PARI
    Vec(1/((1-x)^2*(1-x^2)*(1-x^4)*(1-x^8))+O(x^99)) \\ Charles R Greathouse IV, Sep 03 2011

Formula

a(n) = (8*floor(n/4)^4 + 8*(m+8)*floor(n/4)^3 - 2*(m^3 - 6*m^2 - 19*m - 86)*floor(n/4)^2 -8*(m^3 - 6*m^2 - 6*m - 22)*floor(n/4) - 7*m^3 + 42*m^2 + 13*m + 54 - (m^3 - 6*m^2 + 5*m + 6)*(-1)^floor(n/4))/48 where m = n mod 4. - Luce ETIENNE, Apr 07 2018

A089177 Triangle read by rows: T(n,k) (n >= 0, 0 <= k <= 1+log_2(floor(n))) giving number of non-squashing partitions of n into k parts.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 4, 4, 1, 1, 5, 6, 2, 1, 6, 9, 4, 1, 7, 12, 6, 1, 8, 16, 10, 1, 1, 9, 20, 14, 2, 1, 10, 25, 20, 4, 1, 11, 30, 26, 6, 1, 12, 36, 35, 10, 1, 13, 42, 44, 14, 1, 14, 49, 56, 20, 1, 15, 56, 68, 26, 1, 16, 64, 84, 36, 1, 1, 17, 72, 100, 46, 2, 1, 18, 81, 120, 60, 4, 1
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2003

Keywords

Comments

T(n,k) = A181322(n,k) - A181322(n,k-1) for n>0. - Alois P. Heinz, Jan 25 2014

Examples

			Triangle begins:
  1;
  1, 1;
  1, 2,  1;
  1, 3,  2;
  1, 4,  4,  1;
  1, 5,  6,  2;
  1, 6,  9,  4;
  1, 7, 12,  6;
  1, 8, 16, 10,  1;
		

Crossrefs

Cf. A078121, A089178. Columns give A002620, A008804, A088932, A088954. Row sums give A000123.

Programs

  • Maple
    T:= proc(n) option remember;
         `if`(n=0, 1, zip((x, y)-> x+y, [T(n-1)], [0, T(floor(n/2))], 0)[])
        end:
    seq(T(n), n=0..25);  # Alois P. Heinz, Apr 01 2012
  • Mathematica
    row[0] = {1}; row[1] = {1, 1}; row[n_] := row[n] = Plus @@ PadRight[ {row[n-1], Join[{0}, row[Floor[n/2]]]} ]; Table[row[n], {n, 0, 25}] // Flatten (* Jean-François Alcover, Jan 31 2014 *)

Formula

Row 0 = {1}, row 1 = {1 1}; for n >=2, row n = row n-1 + (row floor(n/2) shifted one place right).
G.f. for column k (k >= 2): x^(2^(k-2))/((1-x)*Product_{j=0..k-2} (1-x^(2^j))). [corrected by Jason Yuen, Jan 12 2025]
Conjecture: let R(n,x) be the n-th reversed row polynomial, then R(n,x) = Sum_{k=0..A000523(A053645(n)) + 1} T(A053645(n),k)*R(2^(A000523(n)-k),x) for n > 0, n != 2^m with R(0,x) = 1 where R(2^m,x) is the (m+1)-th row polynomial of A078121. - Mikhail Kurkov, Jun 28 2025

Extensions

More terms from Alford Arnold, May 22 2004
Showing 1-3 of 3 results.