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.

A183011 (24n - 1)p(n): traces of partition class polynomials, with a(0) = -1.

Original entry on oeis.org

-1, 23, 94, 213, 475, 833, 1573, 2505, 4202, 6450, 10038, 14728, 22099, 31411, 45225, 63184, 88473, 120879, 165935, 222950, 300333, 398376, 528054, 691505, 905625, 1172842, 1517628, 1947470, 2494778, 3172675, 4029276, 5083606, 6403683, 8023113
Offset: 0

Views

Author

Omar E. Pol, Jan 21 2011

Keywords

Comments

a(n) is also Tr(n), the numerator of the finite algebraic formula for the number of partitions of n, if n >= 1. The formula is p(n) = Tr(n)/(24*n - 1), n >= 1. See theorem 1.1 of the Bruinier-Ono paper in the link. For the denominators see A183010.
a(n) is also the coefficient of the second term (the trace) in the n-th Bruinier-Ono "partition polynomial" H_n(x), if n >= 1. See the Bruinier-Ono paper, theorem 1.1 and chapter 5 "Examples". For the coefficients of the 4th terms see A187218. - Omar E. Pol, Jul 10 2011
In the Bruinier-Ono-Sutherland paper (Jan 23 2013) partition polynomials are called "partition class polynomials". See also Sutherland's table of Hpart_n(x) in link section. - Omar E. Pol, Feb 20 2013

Examples

			1. For n = 6, the number of partitions of 6 is 11, so a(6) = (24*6 - 1)*11 = 143*11 = 1573.
2. For n = 1, in the Bruinier-Ono paper, chapter 5, the first "partition polynomial" is H_1(x) = x^3 - 23*x^2 + (3592/23)*x - 419. The coefficient of the second term (the trace) is 23, so a(1) = 23.
G.f. = -1 + 23*x + 94*x^2 + 213*x^3 + 475*x^4 + 833*x^5 + 1573*x^6 + 2505*x^7 + ...
G.f. = -q^-1 + 23*q^23 + 94*q^47 + 213*q^71 + 475*q^95 + 833*q^119 + 1573*q^143 + ...
		

Crossrefs

Positive terms are the partial sums of A183012, also the column 24 of A182729.

Programs

  • Mathematica
    a[ n_] := (24 n - 1) SeriesCoefficient[ 1 / QPochhammer[ x], {x, 0, n}]; (* Michael Somos, Jun 26 2017 *)
  • PARI
    {a(n) = if( n<0, 0, (24*n - 1) * numbpart(n))}; /* Michael Somos, Aug 28 2013 */

Formula

a(n) = A183010(n)*A000041(n).
a(n) = 24*A066186(n) - A000041(n) = A183009(n) - A000041(n) = (A008606(n)-1)*A000041(n).
a(n) = 12M_2(n) - p(n) = 24spt(n) + 12N_2(n) - p(n) = 12*A220909(n) - A000041(n) = 24*A092269(n) + 12*A220908(n) - A000041(n), n >= 1. - Omar E. Pol, Feb 17 2013
G.f.: Sum_{k >= 0} a(k) * q^(24*k - 1) = q * d/dq (1/q * Product_{k > 0} 1 / (1 - q^(24*k))). - Michael Somos, Aug 28 2013

A182727 Sum of largest parts of the shell model of partitions with n regions.

Original entry on oeis.org

1, 3, 6, 8, 12, 15, 20, 22, 26, 29, 35, 38, 43, 47, 54, 56, 60, 63, 69, 74, 78, 86, 89, 94, 98, 105, 108, 114, 119, 128, 130, 134, 137, 143, 148, 152, 160, 164, 171, 177, 182, 192, 195, 200, 204, 211, 214, 220, 225, 234, 239, 243, 251, 258, 264, 275, 277, 281
Offset: 1

Views

Author

Omar E. Pol, Jan 25 2011

Keywords

Comments

Question: Is there some connection with fractals?

Examples

			For n = 6 the largest parts of the first six regions of the shell model of partitions are 1, 2, 3, 2, 4, 3, so a(6) = 1+2+3+2+4+3 = 15.
Written as a triangle begins:
1;
3;
6;
8,   12;
15,  20;
22,  26, 29, 35;
38,  43, 47, 54;
56,  60, 63, 69, 74, 78, 86;
89,  94, 98,105,108,114,119,128;
130,134,137,143,148,152,160,164,171,177,182,192;
195,200,204,211,214,220,225,234,239,243,251,258,264,275;
		

Crossrefs

Partial sums of A141285. Row j has length A187219(j). Right border gives A006128.

Formula

a(A000041(n)) = A182181(A000041(n)) = A006128(n). - Omar E. Pol, May 24 2012

Extensions

New name from Omar E. Pol, Apr 26 2012

A182728 Array T(n,k) = n*k*A000041(n) read by antidiagonals, n,k >= 1.

Original entry on oeis.org

1, 4, 2, 9, 8, 3, 20, 18, 12, 4, 35, 40, 27, 16, 5, 66, 70, 60, 36, 20, 6, 105, 132, 105, 80, 45, 24, 7, 176, 210, 198, 140, 100, 54, 28, 8, 270, 352, 315, 264, 175, 120, 63, 32, 9, 420, 540, 528, 420, 330, 210, 140, 72, 36, 10, 616, 840, 810, 704, 525, 396, 245, 160, 81, 40, 11
Offset: 1

Views

Author

Omar E. Pol, Jan 22 2011

Keywords

Examples

			Array begins:
    1,   2,   3,   4,   5,   6,   7, ...
    4,   8,  12,  16,  20,  24,  28, ...
    9,  18,  27,  36,  45,  54,  63, ...
   20,  40,  60,  80, 100, 120, 140, ...
   35,  70, 105, 140, 175, 210, 245, ...
   66, 132, 198, 264, 330, 396, 462, ...
  105, 210, 315, 420, 525, 630, 735, ...
		

Crossrefs

Column 1 gives A066186. Column 24 gives A183009.

Programs

  • Maple
    A182728 := proc(n,k) n*k*combinat[numbpart](n) ; end proc:
    seq(seq( A182728(d+1-k, k), k=1..d), d=1..10) ; # R. J. Mathar, Feb 01 2011

A182724 Sum of all parts of all partitions of n minus the number of partitions of n.

Original entry on oeis.org

0, 2, 6, 15, 28, 55, 90, 154, 240, 378, 560, 847, 1212, 1755, 2464, 3465, 4752, 6545, 8820, 11913, 15840, 21042, 27610, 36225, 46992, 60900, 78260, 100386, 127820, 162516, 205260, 258819, 324576, 406230, 506022, 629195, 778932, 962555, 1185030
Offset: 1

Views

Author

Omar E. Pol, Jan 30 2011

Keywords

Comments

a(n) is the sum of (the zeroth moments of) all partitions of n minus the partition number of n.

Examples

			a(7) = 90 = (7-1)*15 = 105 - 15, because the number of partitions of 7 is 15 and the sum of all parts of all partitions of 7 is 7*15 = 105.
		

Crossrefs

Cf. A000041, A066186. Column 1 of A182729.

Programs

  • Maple
    a:= n-> (n-1) *combinat[numbpart](n):
    seq (a(n), n =1..50);
  • Mathematica
    pnxt[n_]:=Module[{ps=IntegerPartitions[n]},Total[Flatten[ps]]- Length[ps]]; Array[pnxt,40] (* Harvey P. Dale, Jul 15 2011 *)
    Table[(n-1)PartitionsP[n],{n,40}] (* Harvey P. Dale, Jan 17 2015 *)

Formula

a(n) = (n-1)*A000041(n) = A066186(n) - A000041(n).
Showing 1-4 of 4 results.