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.

A096401 Number of balanced partitions of n into distinct parts: least part is equal to number of parts.

Original entry on oeis.org

1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 8, 8, 10, 11, 13, 14, 17, 18, 21, 23, 26, 28, 32, 35, 39, 43, 48, 53, 59, 65, 72, 80, 88, 97, 107, 118, 129, 142, 155, 171, 186, 204, 222, 244, 265, 290, 315, 345, 374, 409, 443, 484, 524, 571, 618, 673, 727, 790
Offset: 1

Views

Author

Vladeta Jovovic, Aug 06 2004

Keywords

Examples

			a(14)=3 because we have 12+2, 7+4+3 and 6+5+3.
		

Crossrefs

Programs

  • Maple
    G:=sum((x^(m*(3*m-1)/2)-x^(m*(3*m+1)/2))/product(1-x^i,i=1..m),m=1..20): Gser:=series(G,x=0,80): seq(coeff(Gser,x^n),n=1..78); # Emeric Deutsch, Mar 29 2005
  • PARI
    my(N=99, x='x+O('x^N)); Vec(sum(k=1, N, x^(k*(3*k-1)/2)/prod(j=1, k-1, 1-x^j))) \\ Seiichi Manyama, Jan 15 2022

Formula

G.f.: Sum_{m>=1} (x^(m*(3*m-1)/2)-x^(m*(3*m+1)/2))/Product_{i=1..m} (1-x^i).
a(n) = A025157(n) - A237979(n) = A237977(n) - A237976(n) for n > 0. - Seiichi Manyama, Jan 13 2022
a(n) ~ (1 - A263719) * A025157(n). - Vaclav Kotesovec, Jan 15 2022

Extensions

More terms from Emeric Deutsch, Mar 29 2005

A237979 Number of strict partitions of n such that (least part) > number of parts.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 7, 7, 9, 10, 12, 13, 16, 17, 20, 22, 25, 28, 32, 35, 40, 45, 50, 56, 63, 70, 78, 87, 96, 107, 118, 131, 144, 160, 175, 194, 213, 235, 257, 284, 310, 342, 373, 410, 447, 491, 534, 585, 637, 696, 756, 826, 896, 977, 1060, 1153, 1250, 1359, 1471, 1597, 1729, 1874, 2026, 2195, 2371, 2565
Offset: 1

Views

Author

Clark Kimberling, Feb 18 2014

Keywords

Comments

Also the number of partitions into distinct parts with minimal part >= 2 and difference between parts >= 3. [Joerg Arndt, Mar 31 2014]

Examples

			a(9) = 3 counts these partitions:  9, 63, 54.
		

Crossrefs

Programs

  • Mathematica
    z = 50; q[n_] := q[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
    p1[p_] := p1[p] = DeleteDuplicates[p]; t[p_] := t[p] = Length[p1[p]]
    Table[Count[q[n], p_ /; Min[p] < t[p]], {n, z}]  (* A237976 *)
    Table[Count[q[n], p_ /; Min[p] <= t[p]], {n, z}] (* A237977 *)
    Table[Count[q[n], p_ /; Min[p] == t[p]], {n, z}] (* A096401 *)
    Table[Count[q[n], p_ /; Min[p] > t[p]], {n, z}]  (* A237979 *)
    Table[Count[q[n], p_ /; Min[p] >= t[p]], {n, z}] (* A025157 *)
  • PARI
    N=66; q='q+O('q^N); Vec(-1+sum(n=0, N, q^(n*(3*n+1)/2) / prod(k=1, n, 1-q^k ) )) \\ Joerg Arndt, Mar 09 2014

Formula

G.f. with a(0)=0: sum(n>=0, q^(n*(3*n+1)/2) / prod(k=1..n, 1-q^k ) ). [Joerg Arndt, Mar 09 2014]
a(n) ~ c^(1/4) * exp(2*sqrt(c*n)) / (2*sqrt(Pi*(1 + 3*r^2)) * n^(3/4)), where r = A263719 and c = 3*(log(r))^2/2 + polylog(2, 1-r). - Vaclav Kotesovec, Jan 15 2022
a(n) ~ A263719 * A025157(n). - Vaclav Kotesovec, Jan 15 2022

A237976 Number of strict partitions of n such that (least part) < number of parts.

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 2, 2, 3, 4, 6, 7, 9, 11, 14, 17, 21, 25, 31, 37, 45, 54, 64, 76, 90, 106, 124, 146, 170, 198, 230, 267, 308, 357, 410, 472, 542, 621, 709, 811, 923, 1051, 1194, 1355, 1534, 1738, 1962, 2215, 2497, 2812, 3161, 3553, 3986, 4469, 5005, 5600, 6258
Offset: 0

Views

Author

Clark Kimberling, Feb 18 2014

Keywords

Examples

			a(8) = 3 counts these partitions:  71, 521, 431.
		

Crossrefs

Programs

  • Mathematica
    z = 50; q[n_] := q[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
    p1[p_] := p1[p] = DeleteDuplicates[p]; t[p_] := t[p] = Length[p1[p]]
    Table[Count[q[n], p_ /; Min[p] < t[p]], {n, z}]  (* A237976 *)
    Table[Count[q[n], p_ /; Min[p] <= t[p]], {n, z}] (* A237977 *)
    Table[Count[q[n], p_ /; Min[p] == t[p]], {n, z}] (* A096401 *)
    Table[Count[q[n], p_ /; Min[p] > t[p]], {n, z}]  (* A237979 *)
    Table[Count[q[n], p_ /; Min[p] >= t[p]], {n, z}] (* A025157 *)
  • PARI
    my(N=66, x='x+O('x^N)); concat([0, 0, 0], Vec(sum(k=0, N, x^(k*(k+1)/2)*(1-x^(k*(k-1)))/prod(j=1, k, 1-x^j)))) \\ Seiichi Manyama, Jan 13 2022

Formula

G.f.: Sum_{k>=0} x^(k*(k+1)/2) * (1-x^(k*(k-1))) / Product_{j=1..k} (1-x^j). - Seiichi Manyama, Jan 13 2022
a(n) = A000009(n) - A025157(n). - Vaclav Kotesovec, Jan 18 2022

Extensions

Prepended a(0)=0, Seiichi Manyama, Jan 13 2022
Showing 1-3 of 3 results.