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.

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A344088 Flattened tetrangle of reversed strict integer partitions sorted first by sum, then colexicographically.

Original entry on oeis.org

1, 2, 1, 2, 3, 1, 3, 4, 2, 3, 1, 4, 5, 1, 2, 3, 2, 4, 1, 5, 6, 1, 2, 4, 3, 4, 2, 5, 1, 6, 7, 1, 3, 4, 1, 2, 5, 3, 5, 2, 6, 1, 7, 8, 2, 3, 4, 1, 3, 5, 4, 5, 1, 2, 6, 3, 6, 2, 7, 1, 8, 9, 1, 2, 3, 4, 2, 3, 5, 1, 4, 5, 1, 3, 6, 4, 6, 1, 2, 7, 3, 7, 2, 8, 1, 9, 10
Offset: 0

Views

Author

Gus Wiseman, May 12 2021

Keywords

Comments

The zeroth row contains only the empty partition.
A tetrangle is a sequence of finite triangles.

Examples

			Tetrangle begins:
  0: ()
  1: (1)
  2: (2)
  3: (12)(3)
  4: (13)(4)
  5: (23)(14)(5)
  6: (123)(24)(15)(6)
  7: (124)(34)(25)(16)(7)
  8: (134)(125)(35)(26)(17)(8)
  9: (234)(135)(45)(126)(36)(27)(18)(9)
		

Crossrefs

Positions of first appearances are A015724.
Triangle sums are A066189.
The non-strict version is A080576.
Taking lex instead of colex gives A246688 (non-reversed: A344086).
The non-reversed version is A344087.
Taking revlex instead of colex gives A344089 (non-reversed: A118457).
A026793 gives reversed strict partitions in A-S order (sum/length/lex).
A319247 sorts strict partitions by Heinz number.
A329631 sorts reversed strict partitions by Heinz number.
A344090 gives strict partitions in A-S order (sum/length/lex).

Programs

  • Mathematica
    colex[f_,c_]:=OrderedQ[PadRight[{Reverse[f],Reverse[c]}]];
    Table[Sort[Reverse/@Select[IntegerPartitions[n],UnsameQ@@#&],colex],{n,0,10}]

A116682 Sum of the odd parts in all partitions of n into distinct parts.

Original entry on oeis.org

0, 1, 0, 4, 4, 9, 10, 17, 26, 38, 50, 66, 92, 116, 154, 203, 264, 326, 416, 514, 644, 802, 986, 1198, 1474, 1784, 2156, 2608, 3124, 3728, 4454, 5286, 6266, 7420, 8736, 10279, 12062, 14106, 16472, 19214, 22330, 25914, 30032, 34714, 40058, 46208, 53136
Offset: 0

Views

Author

Emeric Deutsch, Feb 22 2006

Keywords

Examples

			a(9)=38 because in the partitions of 9 into distinct parts, namely, [9],[8,1],[7,2],[6,3],[6,2,1],[5,4],[5,3,1] and [4,3,2], the sum of the odd parts is 9+1+7+3+1+5+5+3+1+3=38.
		

Crossrefs

Programs

  • Maple
    f:=product(1+x^j,j=1..70)*sum((2*j-1)*x^(2*j-1)/(1+x^(2*j-1)),j=1..40): fser:=series(f,x=0,60): seq(coeff(fser,x,n),n=0..50);
  • Mathematica
    d[n_] := d[n] = Select[IntegerPartitions[n], DeleteDuplicates[#] == # &]
    Map[Total[Select[Flatten[d[#]], OddQ]] &, -1 + Range[30]]  (* Peter J. C. Moses, Mar 14 2014 *)
    (* or *)
    CoefficientList[Series[QPochhammer[-1, x]*(1 + EllipticTheta[2, 0, x]^4 - EllipticTheta[4, 0, x]^4)/48, {x, 0, 100}], x] (* Vaclav Kotesovec, Jun 24 2025 *)

Formula

a(n) = Sum_{k=0..n} k*A116681(n,k).
G.f.: (Product_{j>=1} 1+x^j)*(Sum_{j>=1} (2*j-1)*x^(2*j-1)/(1+x^(2*j-1))).
a(n) + A116684(n) = A066189(n) = n*A000009(n). - Vaclav Kotesovec, Jun 24 2025
a(n) = Sum_{k=0..floor(n/2)} A000700(n-2*k) * A000009(2*k) * (n - 2*k). - David A. Corneth, Jun 24 2025

A116684 Sum of the even parts in all partitions of n into distinct parts.

Original entry on oeis.org

0, 0, 2, 2, 4, 6, 14, 18, 22, 34, 50, 66, 88, 118, 154, 202, 248, 320, 412, 512, 636, 794, 972, 1194, 1454, 1766, 2134, 2576, 3092, 3696, 4426, 5254, 6214, 7364, 8672, 10196, 11986, 14014, 16360, 19084, 22190, 25746, 29860, 34516, 39846, 45952, 52848
Offset: 0

Views

Author

Emeric Deutsch, Feb 22 2006

Keywords

Examples

			a(9)=34 because in the partitions of 9 into distinct parts, namely, [9],[8,1],[7,2],[6,3],[6,2,1],[5,4],[5,3,1] and [4,3,2], the sum of the even parts is 8+2+6+6+2+4+4+2=34.
		

Crossrefs

Programs

  • Maple
    f:=2*product(1+x^j,j=1..60)*sum((j*x^(2*j)/(1+x^(2*j)),j=1..35)): fser:=series(f,x=0,55): seq(coeff(fser,x,n),n=0..50);
  • Mathematica
    d[n_] := d[n] = Select[IntegerPartitions[n], DeleteDuplicates[#] == # &]
    Map[Total[Select[Flatten[d[#]], EvenQ]] &, -1 + Range[30]]  (* Peter J. C. Moses, Mar 14 2014 *)
    (* or *)
    CoefficientList[Series[QPochhammer[-1, x]*(EllipticTheta[3, 0, x]^4 + EllipticTheta[4, 0, x]^4 - 2)/48, {x, 0, 100}], x] (* Vaclav Kotesovec, Jun 24 2025 *)

Formula

a(n) = Sum_{k>=0} k*A116683(n,k).
G.f.: 2*(Product_{j>=1} 1+x^j)*(Sum_{j>=1} j*x^(2*j)/(1+x^(2*j))).
A116682(n) + a(n) = A066189(n) = n*A000009(n). - Vaclav Kotesovec, Jun 24 2025
a(n) = Sum_{k=0..floor(n/2)} A000700(n-2*k) * A000009(2*k) * (2*k). - David A. Corneth, Jun 24 2025

A277029 Convolution of A000203 and A000009.

Original entry on oeis.org

0, 1, 4, 8, 16, 25, 42, 61, 90, 130, 178, 242, 332, 436, 566, 747, 952, 1210, 1540, 1926, 2400, 2994, 3674, 4506, 5526, 6708, 8108, 9808, 11768, 14080, 16850, 20022, 23738, 28128, 33152, 39015, 45854, 53662, 62696, 73166, 85118, 98826, 114636, 132586, 153102
Offset: 0

Views

Author

Vaclav Kotesovec, Sep 25 2016

Keywords

Comments

Apart from initial zero this is the convolution of A340793 and A036469. - Omar E. Pol, Feb 16 2021

Crossrefs

Cf. A066186 (convolution of A000203 and A000041).
Cf. A276432 (convolution of A000203 and A000219).

Programs

  • Mathematica
    Table[Sum[DivisorSigma[1, k] * PartitionsQ[n-k], {k,1,n}], {n,0,50}]
    nmax = 50; CoefficientList[Series[Sum[j*x^j/(1-x^j), {j, 1, nmax}]*Product[1+x^k, {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{j>=1} (j*x^j/(1-x^j))*Product_{k>=1} (1+x^k).
a(n) ~ 2*n*A000009(n) ~ exp(Pi*sqrt(n/3)) * n^(1/4) / (2*3^(1/4)).

A306923 Sum over all partitions of n into distinct parts of the bitwise AND of the parts.

Original entry on oeis.org

0, 1, 2, 3, 5, 7, 7, 7, 12, 18, 18, 22, 23, 25, 19, 26, 37, 49, 55, 64, 67, 78, 80, 93, 101, 110, 106, 122, 114, 129, 136, 158, 197, 237, 256, 287, 311, 337, 367, 403, 424, 453, 492, 525, 571, 638, 684, 754, 809, 853, 896, 955, 995, 1075, 1149, 1226, 1295, 1412
Offset: 0

Views

Author

Alois P. Heinz, Mar 16 2019

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, r) option remember; `if`(i*(i+1)/2 `if`(i b(n$2, 2^ilog2(2*n)-1):
    seq(a(n), n=0..57);

A306924 Sum over all partitions of n into distinct parts of the bitwise OR of the parts.

Original entry on oeis.org

0, 1, 2, 6, 7, 13, 20, 35, 42, 58, 75, 104, 133, 176, 233, 327, 402, 500, 616, 762, 916, 1112, 1329, 1640, 1967, 2350, 2787, 3352, 3960, 4706, 5571, 6706, 7922, 9374, 10982, 12933, 15090, 17578, 20322, 23692, 27391, 31626, 36308, 41788, 47799, 54704, 62258
Offset: 0

Views

Author

Alois P. Heinz, Mar 16 2019

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, r) option remember; `if`(i*(i+1)/2 `if`(i b(n$2, 0):
    seq(a(n), n=0..49);

A306925 Sum over all partitions of n into distinct parts of the bitwise XOR of the parts.

Original entry on oeis.org

0, 1, 2, 6, 6, 11, 16, 35, 36, 46, 50, 84, 94, 130, 158, 285, 338, 424, 460, 616, 672, 810, 816, 1162, 1346, 1680, 1754, 2308, 2562, 3164, 3288, 4486, 5306, 6838, 7522, 9627, 11006, 13496, 14200, 17462, 19682, 24036, 25650, 30842, 33884, 40302, 41644, 48896
Offset: 0

Views

Author

Alois P. Heinz, Mar 16 2019

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, r) option remember; `if`(i*(i+1)/2 `if`(i b(n$2, 0):
    seq(a(n), n=0..51);

Formula

a(n) is odd <=> n in { A067589 }.
a(n) is odd <=> A067588(n) is odd.

A325515 Sum of sums of omegas of the parts over all strict integer partitions of n.

Original entry on oeis.org

0, 0, 1, 2, 3, 5, 8, 11, 14, 22, 29, 37, 50, 63, 81, 106, 129, 160, 203, 246, 303, 373, 449, 541, 654, 782, 932, 1116, 1322, 1559, 1848, 2167, 2537, 2978, 3470, 4041, 4706, 5449, 6303, 7291, 8402, 9665, 11117, 12744, 14592, 16708, 19062, 21730, 24757, 28141
Offset: 0

Views

Author

Gus Wiseman, May 07 2019

Keywords

Comments

Also omega of the product of products of parts over all strict integer partitions of n.
The omega of n is A001222(n), the number of prime factors of n counted with multiplicity.

Crossrefs

Programs

  • Mathematica
    Table[Sum[Total[PrimeOmega/@s],{s,Select[IntegerPartitions[n],UnsameQ@@#&]}],{n,0,30}]

Formula

a(n) = A001222(A325504(n)).

A304797 Expansion of x * (d/dx) Sum_{k>=0} k!*x^(k*(k+1)/2)/Product_{j=1..k} (1 - x^j).

Original entry on oeis.org

0, 1, 2, 9, 12, 25, 66, 91, 152, 243, 570, 715, 1212, 1729, 2702, 5265, 6960, 10489, 15318, 22363, 31100, 57771, 72534, 109411, 151032, 219025, 293930, 421281, 680820, 883369, 1256010, 1727971, 2396000, 3235419, 4447506, 5894875, 9266580, 11691001, 16380470, 21774753
Offset: 0

Views

Author

Ilya Gutkovskiy, May 18 2018

Keywords

Comments

Sum of all parts of all compositions (ordered partitions) of n into distinct parts.

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<0 or n<0, 0,
         `if`(k=0, `if`(n=0, 1, 0), b(n-k, k) +k*b(n-k, k-1)))
        end:
    a:= n-> n*add(b(n, k), k=0..floor((sqrt(8*n+1)-1)/2)):
    seq(a(n), n=0..50);  # Alois P. Heinz, May 18 2018
  • Mathematica
    nmax = 39; CoefficientList[Series[x D[Sum[k! x^(k (k + 1)/2)/Product[1 - x^j, {j, 1, k}], {k, 0, nmax}], x], {x, 0, nmax}], x]

Formula

a(n) = n*A032020(n).

A306919 Sum over all partitions of n into distinct parts of the power tower evaluation x^y^...^z, where x, y, ..., z are the parts in increasing order.

Original entry on oeis.org

1, 1, 2, 4, 5, 14, 24, 122, 318, 2417851639229258349414245, 14134776518227074636666380005943348126619871175004951664972849610340964762
Offset: 0

Views

Author

Alois P. Heinz, Mar 16 2019

Keywords

Examples

			a(0) = 1 because the empty partition () has no parts, the exponentiation operator ^ is right-associative, and 1 is the right identity of exponentiation.
a(6) = 1^2^3 + 2^4 + 1^5 + 6 = 1 + 16 + 1 + 6 = 24.
		

Crossrefs

Programs

  • Maple
    d:= proc(l) local i; for i to nops(l)-1 do
           if l[i]=l[i+1] then return fi od; l
        end:
    f:= l-> `if`(l=[], 1, l[1]^f(subsop(1=(), l))):
    a:= n-> add(f(l), l=map(l->d(sort(l, `<`)), combinat[partition](n))):
    seq(a(n), n=0..11);
  • Mathematica
    d[l_] := Module[{i}, For[i = 1, i <= Length[l]-1 , i++, If[l[[i]] == l[[i+1]], Return[]]]; l];
    f[l_] := If[l == {}, 1, l[[1]]^f[Delete[l, 1]]];
    a[n_] := Sum[f[l], {l, Sort /@ Select[IntegerPartitions[n], Length@# == Length @ Union@#&]}];
    a /@ Range[0, 11] (* Jean-François Alcover, May 03 2020, after Maple *)
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