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.

A259094 From the Lecture Hall Theorem: array read by antidiagonals: T(n,k) = number of partitions of n into odd parts of size < 2k.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 2, 2, 3, 3, 1, 1, 1, 1, 2, 2, 3, 4, 3, 1, 1, 1, 1, 2, 2, 3, 4, 4, 3, 1, 1, 1, 1, 2, 2, 3, 4, 5, 5, 4, 1, 1, 1, 1, 2, 2, 3, 4, 5, 6, 6, 4, 1, 1, 1, 1, 2, 2, 3, 4, 5, 6, 7, 7, 4, 1, 1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 9, 8, 5, 1
Offset: 1

Views

Author

N. J. A. Sloane, Jun 19 2015

Keywords

Comments

The Lecture Hall Theorem states that (the number of partitions (d1,d2,...,dn) of m such that 0 <= d1/1 <= d2/2 <= ... <= dn/n) equals (the number of partitions of m into odd parts less than 2n).

Examples

			The array begins:
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 ...
  1,1,1,2,2,2,3,3,3,4,4,4,5,5,5,6,6,6,7,7,7,8,8,8,9,9,9,10,10,10,11,11,11,12,12,12,13,13,13,14 ...
  1,1,1,2,2,3,4,4,5,6,7,8,9,10,11,13,14,15,17,18,20,22,23,25,27,29,31,33,35,37,40,42,44,47,49,52,55 ...
  1,1,1,2,2,3,4,5,6,7,9,10,12,14,16,19,21,24,27,30,34,38,42,46,51,56,61,67,73,79,86,93,100,108,116 ...
  1,1,1,2,2,3,4,5,6,8,10,11,14,16,19,23,26,30,35,40,45,52,58,65,74,82,91,102,113,124,138,151,165,182 ...
  1,1,1,2,2,3,4,5,6,8,10,12,15,17,21,25,29,34,40,46,53,62,70,80,91,103,116,131,147,164,184,204,227 ...
  1,1,1,2,2,3,4,5,6,8,10,12,15,18,22,26,31,36,43,50,58,68,78,90,103,118,134,153,173,195,220,247,277 ...
  1,1,1,2,2,3,4,5,6,8,10,12,15,18,22,27,32,37,45,52,61,72,83,96,111,128,146,168,191,217,247,279,314 ...
  ...
The successive antidiagonals are:
  [1]
  [1, 1]
  [1, 1, 1]
  [1, 1, 1, 1]
  [1, 1, 1, 2, 1]
  [1, 1, 1, 2, 2, 1]
  [1, 1, 1, 2, 2, 2, 1]
  [1, 1, 1, 2, 2, 3, 3, 1]
  [1, 1, 1, 2, 2, 3, 4, 3, 1]
  [1, 1, 1, 2, 2, 3, 4, 4, 3, 1]
  [1, 1, 1, 2, 2, 3, 4, 5, 5, 4, 1]
  [1, 1, 1, 2, 2, 3, 4, 5, 6, 6, 4, 1]
  [1, 1, 1, 2, 2, 3, 4, 5, 6, 7, 7, 4, 1]
  [1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 9, 8, 5, 1]
  ...
		

Crossrefs

Many rows of the array are already in the OEIS: A008620, A008672, A008673, A008674, A008675, A287997, A287998, A288000, A288001.

Programs

  • Maple
    G:=n->mul(1/(1-q^(2*i-1)),i=1..n);
    M:=41;
    G2:=n->seriestolist(series(G(n),q,M));
    for n from 1 to 10 do lprint(G2(n)); od:
    H:=n->[seq(G2(n-i+1)[i],i=1..n)];
    for n from 1 to 14 do lprint(H(n)); od:
  • Mathematica
    G[n_] := Product[1/(1-q^(2*i-1)), {i, 1, n}];
    M = 41;
    G2[n_] := CoefficientList[Series[G[n], {q, 0, M}], q];
    For[n = 1, n <= 10, n++; Print[G2[n]]];
    H[n_] := Table[G2[n-i+1][[i]], {i, 1, n}];
    Reap[For[n = 1, n <= 14, n++, Print[H[n]]; Sow[H[n]]]][[2, 1]] // Flatten (* Jean-François Alcover, Jun 04 2017, translated from Maple *)

A029032 Expansion of 1/((1-x)*(1-x^3)*(1-x^4)*(1-x^5)).

Original entry on oeis.org

1, 1, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 17, 20, 23, 27, 31, 35, 40, 45, 51, 57, 63, 70, 78, 86, 94, 103, 113, 123, 134, 145, 157, 170, 183, 197, 212, 227, 243, 260, 278, 296, 315, 335, 356, 378, 400, 423, 448, 473, 499, 526, 554, 583, 613, 644, 676, 709, 743
Offset: 0

Views

Author

Keywords

Comments

a(n) is the number of partitions of n into parts 1, 3, 4, and 5. - David Neil McGrath, Sep 13 2014

Programs

  • Maple
    M := Matrix(13, (i,j)-> if (i=j-1) or (j=1 and member(i, [1, 3, 10, 12])) then 1 elif j=1 and member(i, [6, 7, 13]) then -1 else 0 fi); a := n -> (M^(n))[1,1]; seq (a(n), n=0..49); # Alois P. Heinz, Jul 25 2008
  • Mathematica
    CoefficientList[Series[1/((1-x)(1-x^3)(1-x^4)(1-x^5)),{x,0,50}],x] (* Harvey P. Dale, Jan 04 2012 *)

Formula

a(0)=1, a(1)=1, a(2)=1, a(3)=2, a(4)=3, a(5)=4, a(6)=5, a(7)=6, a(8)=8, a(9)=10, a(10)=12, a(11)=14, a(12)=17, a(n)=a(n-1)+a(n-3)-a(n-6)- a(n-7)+ a(n-10)+a(n-12)-a (n-13). - Harvey P. Dale, Jan 04 2012
From R. J. Mathar, Jun 23 2021: (Start)
a(n)-a(n-1) = A008680(n).
a(n)-a(n-3) = A025772(n).
a(n)-a(n-4) = A008672(n).
a(n)-a(n-5) = A025767(n). (End)
a(n) = 1 + floor((2*n^3+39*n^2+228*n)/720). - Hoang Xuan Thanh, May 29 2025

A025799 Expansion of 1/((1-x^2)*(1-x^3)*(1-x^10)).

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 2, 1, 2, 2, 3, 2, 4, 3, 4, 4, 5, 4, 6, 5, 7, 6, 8, 7, 9, 8, 10, 9, 11, 10, 13, 11, 14, 13, 15, 14, 17, 15, 18, 17, 20, 18, 22, 20, 23, 22, 25, 23, 27, 25, 29, 27, 31, 29, 33, 31, 35, 33, 37, 35, 40, 37, 42, 40, 44, 42, 47, 44, 49, 47, 52, 49, 55, 52, 57, 55, 60, 57
Offset: 0

Views

Author

Keywords

Comments

Number of partitions of n into parts 2, 3, and 10. - Hoang Xuan Thanh, Aug 21 2025

Examples

			G.f. = 1 + x^2 + x^3 + x^4 + x^5 + 2*x^6 + x^7 + 2*x^8 + 2*x^9 + 3*x^10 + 2*x^11 + ...
		

Crossrefs

Programs

  • Mathematica
    A025799[n_] := Floor[(n^2 + 15*n + 3*(-1)^n*(n + 7) + 99)/120];
    Array[A025799, 100, 0] (* Paolo Xausa, Aug 25 2025 *)
  • PARI
    {a(n) = if( n<-14, a(-15 - n), polcoeff( 1 / ((1 - x^2) * (1 - x^3) * (1 - x^10)) + x * O(x^n), n))}; /* Michael Somos, Mar 2003 */
    
  • PARI
    {a(n) = n = (n - 3*(n%2)) / 2; (n^2 + 9*n)\30 + 1}; /* Michael Somos, Nov 16 2005 */

Formula

G.f.: 1/((1-x^2)(1-x^3)(1-x^10)).
a(n) = A008672( A028242(n - 2)). a(2*n + 3) = a(2*n) = A008672(n).- Michael Somos, Mar 2003
a(n) = a(-15 - n) for all n in Z. - Michael Somos, Nov 16 2005
a(n) = floor((n^2 + 15*n + 3*(n+7)*(-1)^n + 99)/120). - Hoang Xuan Thanh, Aug 21 2025

A211524 Number of ordered triples (w,x,y) with all terms in {1,...,n} and w=3x+5y.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 17, 18, 20, 22, 23, 25, 27, 29, 31, 33, 35, 37, 40, 42, 44, 47, 49, 52, 55, 57, 60, 63, 66, 69, 72, 75, 78, 82, 85, 88, 92, 95, 99, 103, 106, 110, 114, 118, 122, 126, 130, 134, 139
Offset: 0

Views

Author

Clark Kimberling, Apr 14 2012

Keywords

Comments

For a guide to related sequences, see A211422.

Crossrefs

Programs

  • Mathematica
    t[n_] := t[n] = Flatten[Table[-w + 3 x + 5 y, {w, 1, n}, {x, 1, n}, {y, 1, n}]]
    c[n_] := Count[t[n], 0]
    t = Table[c[n], {n, 0, 70}]  (* A211524 *)
    FindLinearRecurrence[t]
    LinearRecurrence[{1,0,1,-1,1,-1,0,-1,1},{0,0,0,0,0,0,0,0,1},69] (* Ray Chandler, Aug 02 2015 *)

Formula

a(n) = a(n-1)+a(n-3)-a(n-4)+a(n-5)-a(n-6)-a(n-8)+a(n-9).
G.f.: x^8/((1-x)*(1-x^3)*(1-x^5)).
Showing 1-4 of 4 results.