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 1-5 of 5 results.

A237800 Number of partitions of n such that 2*(least part) >= number of parts.

Original entry on oeis.org

1, 2, 2, 3, 3, 5, 5, 8, 9, 12, 14, 19, 21, 27, 32, 39, 45, 56, 64, 78, 90, 107, 124, 148, 169, 199, 229, 268, 306, 357, 406, 471, 536, 617, 701, 805, 910, 1041, 1177, 1341, 1511, 1717, 1931, 2187, 2457, 2773, 3109, 3503, 3918, 4403, 4919, 5514, 6150, 6881
Offset: 1

Views

Author

Clark Kimberling, Feb 15 2014

Keywords

Examples

			a(7) = 5 counts these partitions: 7, 61, 52, 43, 322.
		

Crossrefs

Programs

  • Mathematica
    z = 55; q[n_] := q[n] = IntegerPartitions[n]; t[p_] := Length[p];
    Table[Count[q[n], p_ /; 2 Min[p] < t[p]], {n, z}]   (* A237758 *)
    Table[Count[q[n], p_ /; 2 Min[p] == t[p]], {n, z}]  (* A237757 *)
    Table[Count[q[n], p_ /; 2 Min[p] > t[p]], {n, z}]   (* A237799 *)
    Table[Count[q[n], p_ /; 2 Min[p] >= t[p]], {n, z}]  (* A237800 *)

A237758 Number of partitions of n such that 2*(least part) < number of parts.

Original entry on oeis.org

0, 0, 1, 2, 4, 6, 10, 14, 21, 30, 42, 58, 80, 108, 144, 192, 252, 329, 426, 549, 702, 895, 1131, 1427, 1789, 2237, 2781, 3450, 4259, 5247, 6436, 7878, 9607, 11693, 14182, 17172, 20727, 24974, 30008, 35997, 43072, 51457, 61330, 72988, 86677, 102785, 121645
Offset: 1

Views

Author

Clark Kimberling, Feb 15 2014

Keywords

Examples

			a(5) = 4 counts these partitions: 311, 221, 2111, 11111.
		

Crossrefs

Programs

  • Mathematica
    z = 55; q[n_] := q[n] = IntegerPartitions[n]; t[p_] := Length[p];
    Table[Count[q[n], p_ /; 2 Min[p] < t[p]], {n, z}]   (* A237758 *)
    Table[Count[q[n], p_ /; 2 Min[p] <= t[p]], {n, z}]  (* A118084 *)
    Table[Count[q[n], p_ /; 2 Min[p] == t[p]], {n, z}]  (* A237757 *)
    Table[Count[q[n], p_ /; 2 Min[p] > t[p]], {n, z}]   (* A237799 *)
    Table[Count[q[n], p_ /; 2 Min[p] >= t[p]], {n, z}]  (* A237800 *)

A237799 Number of partitions of n such that 2*(least part) > number of parts.

Original entry on oeis.org

1, 1, 1, 2, 2, 4, 4, 6, 7, 9, 10, 14, 15, 19, 23, 28, 32, 40, 46, 56, 65, 77, 89, 107, 122, 143, 165, 193, 220, 257, 292, 338, 385, 443, 503, 578, 653, 746, 844, 962, 1083, 1231, 1384, 1567, 1761, 1987, 2227, 2510, 2807, 3153, 3523, 3949, 4403, 4927, 5485
Offset: 1

Views

Author

Clark Kimberling, Feb 15 2014

Keywords

Examples

			a(7) = 4 counts these partitions: 7, 52, 43, 322.
		

Crossrefs

Programs

  • Mathematica
    z = 55; q[n_] := q[n] = IntegerPartitions[n]; t[p_] := Length[p];
    Table[Count[q[n], p_ /; 2 Min[p] < t[p]], {n, z}]   (* A237758 *)
    Table[Count[q[n], p_ /; 2 Min[p] == t[p]], {n, z}]  (* A237757 *)
    Table[Count[q[n], p_ /; 2 Min[p] > t[p]], {n, z}]   (* A237799 *)
    Table[Count[q[n], p_ /; 2 Min[p] >= t[p]], {n, z}]  (* A237800 *)

A118082 Number of partitions of n such that largest part k occurs floor(k/2) times.

Original entry on oeis.org

1, 0, 1, 2, 2, 3, 3, 4, 5, 6, 8, 10, 12, 15, 19, 22, 27, 32, 39, 45, 54, 63, 75, 87, 102, 118, 139, 160, 186, 214, 248, 284, 328, 375, 430, 490, 561, 637, 727, 824, 935, 1058, 1199, 1352, 1528, 1720, 1938, 2177, 2448, 2743, 3079, 3445, 3856, 4307, 4813, 5365, 5985
Offset: 0

Views

Author

Emeric Deutsch, Apr 12 2006

Keywords

Comments

Also number of partitions of n such that if the number of parts is k, then the smallest part is floor(k/2). Example: a(8)=5 because we have [7,1],[6,1,1],[5,2,1],[4,3,1] and [2,2,2,2].

Examples

			a(8)=5 because we have [4,4],[3,2,2,1],[3,2,1,1,1],[3,1,1,1,1,1] and [2,1,1,1,1,1,1].
		

Crossrefs

Programs

  • Maple
    g:=sum(x^(k*floor(k/2))/product(1-x^j,j=1..k-1),k=1..15): gser:=series(g,x=0,65): seq(coeff(gser,x,n),n=0..60);

Formula

G.f.=sum(x^(k*floor(k/2))/product(1-x^j, j=1..k-1), k=1..infinity).

A118083 Number of partitions of n such that largest part k occurs at least floor(k/2) times.

Original entry on oeis.org

1, 1, 2, 3, 4, 5, 7, 8, 11, 13, 17, 20, 26, 30, 38, 45, 55, 64, 79, 91, 110, 128, 152, 176, 209, 240, 282, 325, 379, 434, 505, 576, 666, 760, 873, 993, 1139, 1290, 1473, 1668, 1897, 2141, 2430, 2736, 3095, 3481, 3925, 4404, 4958, 5550, 6232, 6968, 7805, 8710
Offset: 0

Views

Author

Emeric Deutsch, Apr 12 2006

Keywords

Comments

Also number of partitions of n such that if the number of parts is k, then the smallest part is at least floor(k/2). Example: a(8)=11 because we have [8],[7,1],[6,2],[5,3],[4,4],[6,1,1],[5,2,1],[4,3,1],[4,2,2],[3,3,2] and [2,2,2,2].
Also number of partitions of 2*n into distinct parts with either all parts odd or all parts even. - Vladeta Jovovic, Jul 03 2007

Examples

			a(8)=11 because we have [4,4],[3,3,2],[3,3,1,1],[3,2,2,1],[3,2,1,1,1],[3,1,1,1,1,1],[2,2,2,2],[2,2,2,1,1],[2,2,1,1,1,1],[2,1,1,1,1,1,1] and [1,1,1,1,1,1,1,1].
		

Crossrefs

Programs

  • Maple
    g:=sum(x^(k*floor(k/2))/product(1-x^j,j=1..k),k=1..15): gser:=series(g,x=0,65): seq(coeff(gser,x,n),n=0..60);

Formula

G.f.=sum(x^(k*floor(k/2))/product(1-x^j, j=1..k), k=1..infinity).
a(n) = A000700(2*n) + A000009(n), n>0. - Vladeta Jovovic, Jul 03 2007
a(n) ~ (2 + sqrt(2)) * exp(sqrt(n/3)*Pi) / (8*3^(1/4)*n^(3/4)). - Vaclav Kotesovec, Mar 06 2020
Showing 1-5 of 5 results.