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.

Previous Showing 41-47 of 47 results.

A086644 Permanent of the character table of the symmetric group S_n.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, -20834715303936, 602706855887546351616
Offset: 1

Views

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Jul 26 2003

Keywords

Comments

In the Schmidt-Simion reference it is proved that if A000701(n) is odd then a(n) = 0. So a(11)=a(12)=a(13)=0. The computation of a(10) involves a permanent of dimension 42, and it may take a long time for GAP to compute it.

Links

Crossrefs

Cf. A007870.

Programs

  • GAP
    Permanent(Irr(SymmetricGroup(n)));

Extensions

a(9) from Ferenc Szollosi, Jul 25 2014

A132091 Expansion of psi(x^3) * chi(-x^9) / f(-x^2) in powers of x where psi(), chi(), f() are Ramanujan theta functions.

Original entry on oeis.org

1, 0, 1, 1, 2, 1, 3, 2, 5, 3, 7, 5, 10, 7, 14, 11, 20, 15, 27, 22, 37, 30, 49, 42, 66, 56, 86, 75, 113, 99, 146, 131, 189, 170, 241, 221, 308, 283, 389, 363, 492, 460, 616, 583, 771, 732, 958, 918, 1189, 1143, 1467, 1421, 1807, 1756, 2215, 2166, 2711, 2658, 3303, 3256
Offset: 0

Views

Author

Michael Somos, Aug 09 2007

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).
Also number of partitions of n into parts not divisible by 3 with every part repeated at least twice. Conjectured by R. H. Hardin, Jun 06 2009, proved by Max Alekseyev, Jun 06 2009.
The number of partitions of n into parts not divisible by 3 with every part repeated at least twice has g.f. f(x) = Product_{k>=1} (1 + x^(2k) + x^(3*k) + ...) = Product_{k>=1} (1/(1-x^k) - x^k) = Product_{k>=1} (1 - x^k + x^(2*k)) / (1 - x^k). Excluding parts divisible by 3, we have: f(x) / f(x^3) = Product_{k>=1} (1 - x^k + x^(2*k)) * (1 - x^(3*k)) / (1 - x^k) / (1 - x^(3*k) + x^(6*k)) = Product_{k>=1} (1 - x^k + x^(2*k)) * (1 + x^k + x^(2*k)) / (1 - x^(3*k) + x^(6*k)) = Product_{k>=1} (1 + x^(2*k) + x^(4*k)) / (1 - x^(3*k) + x^(6*k)), which matches the definition of this sequence. - Max Alekseyev, Jun 06 2009

Examples

			G.f. = 1 + x^2 + x^3 + 2*x^4 + x^5 + 3*x^6 + 2*x^7 + 5*x^8 + 3*x^9 + ...
G.f. = 1/q + q^23 + q^35 + 2*q^47 + q^59 + 3*q^71 + 2*q^83 + 5*q^95 + ...

Links

Crossrefs

Cf. A000701, A027340.

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ EllipticTheta[ 2, 0, x^(3/2)] / (2 x^(3/8) QPochhammer[ -x^9, x^9] QPochhammer[ x^2]), {x, 0, n}]; (* Michael Somos, Aug 25 2015 *)
nmax=60; CoefficientList[Series[Product[(1-x^(6*k))^2 * (1-x^(9*k)) / ( (1-x^(2*k)) * (1-x^(3*k)) * (1-x^(18*k))) ,{k,1,nmax}],{x,0,nmax}],x] (* Vaclav Kotesovec, Oct 14 2015 *)
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^6 + A)^2 * eta(x^9 + A )/ (eta(x^2+A) * eta(x^3 + A) * eta(x^18 + A)), n))};

Formula

Expansion of q^(1/12) * eta(q^6)^2 * eta(q^9) / ( eta(q^2) * eta(q^3) * eta(q^18)) in powers of q.
Euler transform of period 18 sequence [ 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, ...].
G.f.: Product_{k>0} (1 + x^(2*k) + x^(4*k)) / (1 - x^(3*k) + x^(6*k)).
G.f.: Sum_{k>=0} Product_{0
a(2*n - 1) = A000701(n). a(2*n) = A027340(n) = - Michael Somos, Aug 25 2015
a(n) ~ exp(2*Pi*sqrt(2*n/3)/3) / (2^(3/4) * 3^(5/4) * n^(3/4)). - Vaclav Kotesovec, Oct 14 2015

Extensions

Edited by N. J. A. Sloane, Jun 07 2009

A322014 Heinz numbers of integer partitions with an even number of even parts.

Original entry on oeis.org

1, 2, 4, 5, 8, 9, 10, 11, 16, 17, 18, 20, 21, 22, 23, 25, 31, 32, 34, 36, 39, 40, 41, 42, 44, 45, 46, 47, 49, 50, 55, 57, 59, 62, 64, 67, 68, 72, 73, 78, 80, 81, 82, 83, 84, 85, 87, 88, 90, 91, 92, 94, 97, 98, 99, 100, 103, 105, 109, 110, 111, 114, 115, 118
Offset: 1

Views

Author

Gus Wiseman, Nov 24 2018

Keywords

Comments

The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).

Links

Crossrefs

Cf. A000701, A046682, A056239, A058695, A058696, A108949, A296150, A321753.

Programs

  • Maple
    a:= proc(n) option remember; local k; for k from 1+`if`(n=1,
      0, a(n-1)) while add(`if`(numtheory[pi](i[1])::odd,
      0, i[2]), i=ifactors(k)[2])::odd do od; k
    end:
seq(a(n), n=1..100);  # Alois P. Heinz, Nov 24 2018
  • Mathematica
    primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[200],EvenQ[Count[primeMS[#],_?EvenQ]]&]

A331262 a(n) is the number of balanced-non-self-conjugate partitions of n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 2, 0, 2, 2, 4, 4, 8, 8, 12, 14, 20, 24, 34, 38, 52, 62, 80, 94, 122, 144, 182, 216, 268, 318, 394, 462, 566, 670, 810, 954, 1152, 1352, 1620, 1900, 2262, 2650, 3144, 3668, 4332, 5054, 5940, 6910, 8102, 9404, 10986, 12732, 14824, 17148, 19918
Offset: 1

Views

Author

Omar E. Pol, Jan 13 2020

Keywords

Comments

a(n) is the number of balanced partitions of n (cf. A047993) that are also non-self-conjugate (cf. A330644).

Crossrefs

Cf. A000041, A000700, A000701, A067772, A047993, A330644.

Formula

a(n) = A047993(n) - A000700(n).
a(n) = 2*A067772(n).

A353315 Triangle read by rows where T(n,k) is the number of integer partitions of n with k parts on or below the diagonal (weak non-excedances).

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 2, 1, 0, 1, 1, 2, 2, 1, 0, 1, 2, 2, 3, 2, 1, 0, 1, 2, 3, 3, 3, 2, 1, 0, 1, 3, 4, 4, 4, 3, 2, 1, 0, 1, 3, 6, 5, 5, 4, 3, 2, 1, 0, 1, 4, 7, 8, 6, 6, 4, 3, 2, 1, 0, 1, 4, 9, 10, 9, 7, 6, 4, 3, 2, 1, 0, 1, 6, 10, 14, 12, 10, 8, 6, 4, 3, 2, 1, 0, 1
Offset: 0

Views

Author

Gus Wiseman, May 15 2022

Keywords

Examples

			Triangle begins:
  1
  0  1
  1  0  1
  1  1  0  1
  1  2  1  0  1
  1  2  2  1  0  1
  2  2  3  2  1  0  1
  2  3  3  3  2  1  0  1
  3  4  4  4  3  2  1  0  1
  3  6  5  5  4  3  2  1  0  1
  4  7  8  6  6  4  3  2  1  0  1
  4  9 10  9  7  6  4  3  2  1  0  1
  6 10 14 12 10  8  6  4  3  2  1  0  1
  6 13 16 17 13 11  8  6  4  3  2  1  0  1
  8 15 21 21 19 14 12  8  6  4  3  2  1  0  1
  9 19 24 28 24 20 15 12  8  6  4  3  2  1  0  1
For example, row n = 9 counts the following partitions (empty column indicated by dot):
  9   72   522   3222   22221  222111  2211111  21111111  .  111111111
  54  81   621   4221   32211  321111  3111111
  63  333  711   5211   42111  411111
      432  3321  6111   51111
      441  4311  33111
      531

Links

Crossrefs

Row sums are A000041.
Column k = 0 is A003106.
The strong version is A114088.
The opposite version is A115720/A115994, rank statistic A257990.
The version for permutations is A123125, strong A173018.
The version for compositions is A352522, rank statistic A352515.
The strong opposite version is A353318.
A000700 counts self-conjugate partitions, ranked by A088902.
A001522 counts partitions with a fixed point, ranked by A352827 (unproved).
A008292 is the triangle of Eulerian numbers.
A064428 counts partitions w/o a fixed point, ranked by A352826 (unproved).
A238352 counts reversed partitions by fixed points, rank statistic A352822.
A352490 gives the nonexcedance set of A122111, counted by A000701.
Cf. A002620, A006918, A008290, A008930, A098825, A219282, A238874, A300788, A353319.

Programs

  • Mathematica
    pgeq[y_]:=Length[Select[Range[Length[y]],#>=y[[#]]&]];
Table[Length[Select[IntegerPartitions[n],pgeq[#]==k&]],{n,0,15},{k,0,n}]

A363220 Number of integer partitions of n whose conjugate has the same median.

Original entry on oeis.org

1, 0, 1, 1, 1, 3, 3, 8, 8, 12, 12, 15, 21, 27, 36, 49, 65, 85, 112, 149, 176, 214, 257, 311, 378, 470, 572, 710, 877, 1080, 1322, 1637, 1983, 2416, 2899, 3465, 4107, 4891, 5763, 6820, 8071, 9542, 11289, 13381, 15808, 18710, 22122, 26105, 30737, 36156, 42377
Offset: 1

Views

Author

Gus Wiseman, May 29 2023

Keywords

Comments

The median of a multiset is either the middle part (for odd length), or the average of the two middle parts (for even length).

Examples

			The partition y = (4,3,1,1) has median 2, and its conjugate (4,2,2,1) also has median 2, so y is counted under a(9).
The a(1) = 1 through a(9) = 8 partitions:
  (1)  .  (21)  (22)  (311)  (321)   (511)    (332)     (333)
                             (411)   (4111)   (422)     (711)
                             (3111)  (31111)  (611)     (4221)
                                              (3311)    (4311)
                                              (4211)    (6111)
                                              (5111)    (51111)
                                              (41111)   (411111)
                                              (311111)  (3111111)

Crossrefs

For mean instead of median we have A047993.
For product instead of median we have A325039, ranks A325040.
For union instead of conjugate we have A360245, complement A360244.
Median of conjugate by rank is A363219.
These partitions are ranked by A363261.
A000700 counts self-conjugate partitions, ranks A088902.
A046682 and A352487-A352490 pertain to excedance set.
A122111 represents partition conjugation.
A325347 counts partitions with integer median.
A330644 counts non-self-conjugate partitions (twice A000701), ranks A352486.
A352491 gives n minus Heinz number of conjugate.
Cf. A000975, A067538, A114638, A360068, A360242, A360248, A362617, A362618, A362621, A363223, A363260.

Programs

  • Mathematica
    conj[y_]:=If[Length[y]==0,y,Table[Length[Select[y,#>=k&]],{k,1,Max[y]}]];
Table[Length[Select[IntegerPartitions[n],Median[#]==Median[conj[#]]&]],{n,30}]

A067618 Number of self-conjugate partitions of n into prime parts.

Original entry on oeis.org

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

Views

Author

Naohiro Nomoto, Feb 01 2002

Keywords

Crossrefs

Cf. A000700, A000701, A046682.

Programs

  • Mathematica
    f[0, m_, k_] := 1; f[n_, 0, k_] := If[n==0, 1, 0]; f[n_, m_, k_] := If[n<0||m<0, 0, Module[{r}, f[n, m, k]=f[n, m-1, k]+If[PrimeQ[m+k], Sum[If[PrimeQ[r+k], f[n-r(2m-r), m-r-1, k+r], 0], {r, 1, m}], 0]]]; a[n_] := f[n, Floor[n/4]+1, 0]; (* f[n, m, k] = number of self-conjugate partitions of n with parts <= m such that every part+k is prime *)

Extensions

Edited by Dean Hickerson, Feb 11 2002
Previous Showing 41-47 of 47 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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