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.

A092265 Sum of smallest parts of all partitions of n into distinct parts.

Original entry on oeis.org

1, 2, 4, 5, 8, 10, 14, 16, 23, 26, 34, 40, 50, 58, 74, 83, 102, 120, 142, 164, 198, 226, 266, 308, 359, 412, 482, 548, 634, 730, 834, 950, 1094, 1240, 1416, 1609, 1826, 2068, 2350, 2648, 2994, 3382, 3806, 4280, 4826, 5408, 6070, 6806, 7619, 8522, 9534, 10632
Offset: 1

Views

Author

Vladeta Jovovic, Feb 14 2004

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1,
         `if`(i>n, 0, b(n,i+1)+b(n-i, i+1)))
        end:
    a:= n-> add(j*b(n-j, j+1), j=1..n):
    seq(a(n), n=1..80);  # Alois P. Heinz, Feb 03 2016
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i > n, 0, b[n, i + 1] + b[n - i, i + 1]]]; a[n_] := Sum[j*b[n - j, j + 1], {j, 1, n}]; Table[a[n], {n, 1, 80}] (* Jean-François Alcover, Jan 21 2017, after Alois P. Heinz *)

Formula

G.f.: Sum_{n >= 1} (-1 + Product_{k >= n} 1 + x^k).
G.f.: Sum_{n >= 1} n*x^n*Product_{k >= n+1} (1 + x^k). - Joerg Arndt, Jan 29 2011
G.f.: Sum_{k >= 1} x^(k*(k+1)/2)/(1 - x^k)/Product_{i = 1..k} (1 - x^i). - Vladeta Jovovic, Aug 10 2004
Conjecture: a(n) = A034296(n) + A237665(n+1). - George Beck, May 06 2017
a(n) ~ exp(Pi*sqrt(n/3)) / (2 * 3^(1/4) * n^(3/4)). - Vaclav Kotesovec, May 20 2018

Extensions

More terms from Pab Ter (pabrlos(AT)yahoo.com), May 25 2004

A092316 Sum of largest parts of all partitions of n into odd distinct parts.

Original entry on oeis.org

1, 0, 3, 3, 5, 5, 7, 12, 14, 16, 18, 27, 29, 33, 42, 55, 59, 65, 78, 95, 110, 118, 137, 167, 188, 200, 236, 274, 303, 330, 376, 435, 485, 522, 591, 677, 741, 803, 903, 1022, 1115, 1210, 1345, 1505, 1650, 1784, 1964, 2201, 2393, 2578, 2843, 3143, 3409, 3685, 4034
Offset: 1

Views

Author

Vladeta Jovovic, Feb 15 2004

Keywords

Examples

			a(13) = 29 because the partitions of 13 into distinct odd parts are [13],[9,3,1] and [7,5,1], with sum of largest terms 13+9+7 = 29.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1 or i^2 `if`(t>n, 0, b(n-t, i-1)))(2*i-1) ))
        end:
    a:= n-> add(`if`(j::odd, j*b(n-j, (j-1)/2), 0), j=1..n):
    seq(a(n), n=1..55);  # Alois P. Heinz, Jan 19 2022
  • Mathematica
    nmax = 50; Rest[CoefficientList[Series[Sum[(2*k - 1)*x^(2*k - 1) * Product[1 + x^(2*j - 1), {j, 1, k - 1}], {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Jun 28 2016 *)

Formula

G.f.: Sum_{n>=1} (2*n-1)*x^(2*n-1)*Product_{k=1..n-1} (1+x^(2*k-1)).
a(n) = 2 * A067619(n) - A000700(n). - Seiichi Manyama, Jan 19 2022

Extensions

More terms from Pab Ter (pabrlos(AT)yahoo.com), May 25 2004

A116860 Triangle read by rows: T(n,k) is the number of partitions into distinct odd parts with smallest part k (n>=1, k>=1).

Original entry on oeis.org

1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 1, 0, 1, 0, 1, 3, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Emeric Deutsch, Feb 27 2006

Keywords

Comments

Row 2 has no terms, row 2n-1 has 2n-1 terms, row 4n has 2n-1 terms, row 4n+2 for n>=1 has 2n-1 terms. Row sums are A000700. T(n,1) = A027349(n). Sum_{k>=1} k*T(n,k) = A092319(n).
Within those rows, T(n, k) = 0 occurs with an odd k iff n is odd and 2*floor((n+3)/6) - 1 <= k < n. - Álvar Ibeas, Aug 03 2020

Examples

			T(25,3) = 3 because we have [17,5,3], [15,7,3] and [13,9,3].
Triangle starts:
1;
{};
0,0,1;
1;
0,0,0,0,1;
1;
0,0,0,0,0,0,1;
1,0,1;
		

Crossrefs

Programs

  • Maple
    g:=sum(t^(2*j-1)*x^(2*j-1)*product(1+x^(2*i-1),i=j+1..30),j=1..30): gser:=simplify(series(g,x=0,52)): for n from 1 to 19 do P[n]:=sort(coeff(gser,x^n)) od: d:=proc(n) if n mod 2 = 1 then n elif n=2 then 0 elif n mod 4 = 0 then n/2-1 else n/2-2 fi end: 1; {}; for n from 3 to 19 do seq(coeff(P[n],t^j),j=1..d(n)) od; # yields sequence in triangular form
  • Mathematica
    imax = 20;
    s = Sum[t^(2 j - 1)*x^(2 j - 1)*Product[1 + x^(2 i - 1), {i, j + 1, imax}], {j, 1, imax}] + O[x]^imax;
    Rest /@ DeleteCases[CoefficientList[#, t]& /@ CoefficientList[s, x], {}] // Flatten (* Jean-François Alcover, May 22 2018 *)

Formula

G.f.: Sum_(t^(2*j-1)*x^(2*j-1)*Product_(1+x^(2*i-1), i=j+1..infinity), j=1..infinity).
For k even, T(n, k) = 0. For k odd, T(n, n) = 1 and, if k < n, T(n, k) = Sum_{i > k} T(n - k, i). - Álvar Ibeas, Aug 03 2020
Showing 1-3 of 3 results.