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 31-40 of 47 results. Next

A067136 Number of Young tableaux with n cells whose shape is symmetric.

Original entry on oeis.org

1, 1, 0, 2, 2, 6, 16, 20, 132, 112, 1216, 1440, 12440, 25520, 138048, 476320, 1649312, 9138300, 21842944, 182232248, 345145392, 3805004296, 7002149760, 83299368432, 180168275232, 1907968553776, 5402826994176, 45597877829600
Offset: 0

Views

Author

Naohiro Nomoto, Feb 19 2002

Keywords

Comments

Equivalently, the row lengths are a self-conjugate partition of n.

Examples

			For n = 8; 4+2+1+1 produces 90 tableaux and 3+3+2 produces
42 tableaux. so a(8) = 90+42 = 132.
For n = 5 = 3+1+1 the 6 tableaux are:
123..124..125..135..134..145
4....3....3....2....2....2..
5....5....4....4....5....3..
		

Crossrefs

Formula

a(n) = A000085(n) - 2*A067142(n).
a(n) = A000085(n) - A330645(n). - Omar E. Pol, Jan 11 2020

Extensions

Edited by Franklin T. Adams-Watters, Nov 07 2006

A067357 Number of self-conjugate partitions of 4n+1 into odd parts.

Original entry on oeis.org

1, 1, 2, 2, 2, 3, 4, 4, 5, 6, 6, 8, 10, 10, 12, 14, 15, 18, 20, 22, 26, 29, 32, 36, 40, 44, 50, 56, 60, 68, 76, 82, 92, 101, 110, 122, 134, 146, 160, 176, 191, 210, 230, 248, 272, 296, 320, 350, 380, 410, 446, 484, 522, 566, 612, 660, 715, 772, 830, 896, 966, 1038, 1120
Offset: 0

Views

Author

Naohiro Nomoto, Feb 24 2002

Keywords

Comments

Also number of partitions of n in which even parts are distinct and if k occurs then so does every positive even number less than k (Dean Hickerson). Absolute values of the terms of A053254. - Emeric Deutsch, Feb 10 2006
The number of self-conjugate partitions of n into odd parts is nonzero if and only if n = 4*k + 1 for some nonnegative integer k. - Michael Somos, Jul 25 2015
Also number of C3v plane partitions of n = 3*k + 1 with rank 1 ; equivalently number of self-conjugate integer partitions with (weight-length) = n. - Wouter Meeussen, May 23 2025

Examples

			a(5)=3 because we have [11,1,1,1,1,1,1,1,1,1,1], [9,3,3,1,1,1,1,1,1] and [5,5,5,3,3].
G.f. = 1 + x + 2*x^2 + 2*x^3 + 2*x^4 + 3*x^5 + 4*x^6 + 4*x^7 + 5*x^8 + ...
		

References

  • P. A. MacMahon, Combinatory Analysis, Cambridge Univ. Press, London and New York, Vol. 1, 1915 and Vol. 2, 1916; see vol. 2, p. 260, Article 512.

Crossrefs

Programs

  • Maple
    g:=sum(q^(k*(k+1))/product(1-q^(2*j+1),j=0..k),k=0..8): gser:=series(g,q=0,80): seq(coeff(gser,q,n),n=0..75); # Emeric Deutsch, Feb 10 2006
  • Mathematica
    a[ n_] := If[ n < 0, 0, SeriesCoefficient[ Sum[ x^(k^2 + k) / Product[ 1 - x^i, {i, 1, 2 k + 1, 2}], {k, 0, (Sqrt[ 4 n + 1] - 1) / 2}], {x, 0, n}]]; (* Michael Somos, Jul 25 2015 *)
    Table[Length[Flatten[Table[Select[IntegerPartitions[w], (w-Length[#])== r && TransposePartition[#] == # &],{w,r,1+2r}],1]],{r,1,17}] (* Wouter Meeussen, May 24 2025 *)
  • PARI
    {a(n) = if( n<0, 0, polcoeff( sum(k=0, (sqrtint( 4*n+1) -1) \ 2, x^(k^2 + k) / prod(j=0, k, 1 - x^(2*j+1), 1 + x * O(x^(n - k^2 - k)))), n))}; /* Michael Somos, Jan 27 2008 */
    
  • PARI
    /* Continued Fraction Expansion: */
    {a(n)=local(CF); CF=1+x; for(k=0, n, CF=1/(1 + (-x)^(n-k+1)*(1 - (-x)^(n-k+1))*CF+x*O(x^n))); polcoeff(CF, n)} \\ Paul D. Hanna, Jul 09 2013

Formula

G.f.: Sum_{k>=0} q^(k*(k+1)) / ((1-q) * (1-q^3) ... (1-q^(2*k+1))). - Emeric Deutsch and Dean Hickerson
G.f.: Sum_{k>=0} q^k * (1+q) * (1+q^3) ... (1+q^(2*k-1)). - Dean Hickerson and Vladeta Jovovic
G.f.: 1/(1 - x*(1+x)/(1 + x^2*(1-x^2)/(1 - x^3*(1+x^3)/(1 + x^4*(1-x^4)/(1 - x^5*(1+x^5)/(1 - ...)))))), a continued fraction. - Paul D. Hanna, Jul 09 2013
From Michael Somos, Jul 25 2015: (Start)
Expansion of nu(-x) in powers of x where nu() is a 3rd-order mock theta function.
a(n) = (-1)^n * A053254(n).
a(2*n) = A085140(n).
a(2*n + 1) = A053253(n). (End)
a(n) ~ exp(Pi*sqrt(n/6)) / (2^(3/2)*sqrt(n)). - Vaclav Kotesovec, Jun 15 2019

Extensions

More terms from Emeric Deutsch, Feb 10 2006

A353318 Irregular triangle read by rows where T(n,k) is the number of integer partitions of n with k excedances (parts above the diagonal), zeros omitted.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 4, 1, 6, 1, 9, 1, 1, 12, 2, 1, 16, 5, 1, 20, 9, 1, 25, 16, 1, 30, 25, 1, 36, 39, 1, 1, 42, 56, 2, 1, 49, 80, 5, 1, 56, 109, 10, 1, 64, 147, 19, 1, 72, 192, 32, 1, 81, 249, 54, 1, 90, 315, 84, 1, 100, 396, 129, 1, 1, 110, 489, 190, 2, 1, 121, 600, 275, 5
Offset: 1

Views

Author

Gus Wiseman, May 21 2022

Keywords

Examples

			Triangle begins:
   1
   1   1
   1   2
   1   4
   1   6
   1   9   1
   1  12   2
   1  16   5
   1  20   9
   1  25  16
   1  30  25
   1  36  39   1
   1  42  56   2
   1  49  80   5
   1  56 109  10
For example, row n = 7 counts the following partitions:
  (1111111)  (7)       (43)
             (52)      (331)
             (61)
             (322)
             (421)
             (511)
             (2221)
             (3211)
             (4111)
             (22111)
             (31111)
             (211111)
		

Crossrefs

Row sums are A000041.
Row lengths are A000194, reversed A003056.
Column k = 1 is A002620, reversed A238875.
Column k = 2 is A097701.
The version for permutations is A008292, opposite A123125.
The weak version is A115720/A115994, rank statistic A257990.
The version for compositions is A352524, weak A352525.
The version for reversed partitions is A353319.
A000700 counts self-conjugate partitions, ranked by A088902.
A001522 counts partitions with a fixed point, ranked by A352827 (unproved).
A064428 counts partitions w/o a fixed point, ranked by A352826 (unproved).
A238352 counts reversed partitions by fixed points, rank statistic A352822.

Programs

  • Mathematica
    partsabove[y_]:=Length[Select[Range[Length[y]],#
    				

A067142 One half of the number of Young tableaux with n cells whose shape is asymmetric.

Original entry on oeis.org

0, 0, 1, 1, 4, 10, 30, 106, 316, 1254, 4140, 17128, 63856, 271492, 1126216, 4936608, 22278712, 101330506, 487735440, 2313734596, 11706759352, 58073844300, 305941244576, 1587272257096, 8656011151184, 46886237603400, 263791190603200, 1487539434072976
Offset: 0

Views

Author

Naohiro Nomoto, Feb 19 2002

Keywords

Comments

Equivalently, the row lengths are a non-self-conjugate partition of n.

Examples

			a(4) = 4 = 8/2; the 8 tableaux are:
1..1234..123..124..134..14..12..13
2........4....3....2....2...3...2.
3.......................3...4...4.
4.................................
The two tableaux of size 4 with symmetric shape are excluded:
12..13
34..24
		

Crossrefs

Formula

a(n) = (A000085(n) - A067136(n))/2.
a(n) = A330645(n)/2. - Omar E. Pol, Jan 11 2020

Extensions

Edited by Franklin T. Adams-Watters, Nov 07 2006
a(26)-a(27) from Omar E. Pol, Jan 11 2020

A067627 Triangle T(n,k) = number of conjugacy classes of partitions of n using only k types of piles, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 3, 1, 1, 3, 2, 1, 6, 1, 3, 7, 2, 5, 9, 2, 1, 8, 11, 2, 1, 13, 14, 1, 3, 19, 15, 3, 5, 27, 19, 1, 11, 34, 22, 2, 1, 15, 49, 23, 2, 1, 27, 59, 28, 3, 3, 39, 78, 30, 1, 5, 60, 93, 34, 3, 11, 82, 118, 36, 1, 18, 115, 140, 41, 3, 1, 30, 155, 170, 42, 2, 1, 48
Offset: 1

Views

Author

Naohiro Nomoto, Feb 02 2002

Keywords

Comments

Lengths of rows are 1 1 2 2 2 3 3 3 3 4 4 4 4 4 ... (A003056).

Examples

			Triangle turned on its side begins:
1.1.1.2.1.2.1.2.2..2..1..3..1..2..2....etc A038548
....1.1.3.3.6.7.9.11.14.15.19.22.23....etc A270060
..........1.1.3.5..8.13.19.27.34.49....etc
...................1..1..3..5.11.15....etc
		

Crossrefs

Cf. A000700, A000701, A046682, A060177. Diagonals give A038548. row sums give A046682.

Programs

  • Maple
    compareL := proc(L1,L2)
        if nops(L1) < nops(L2) then
            -1 ;
        elif nops(L1) > nops(L2) then
            1;
        else
            for i from 1 to nops(L1) do
                if op(i,L1) > op(i,L2) then
                    return 1 ;
                elif op(i,L1) < op(i,L2) then
                    return -1 ;
                end if;
            end do:
            0 ;
        end if;
    end proc:
    A067627 := proc(n,k)
        local a,p,s,pc ;
        a := 0 ;
        for p in combinat[partition](n) do
            s := convert(p,set) ;
            if nops(s) = k then
                pc := combinat[conjpart](p) ;
                if compareL(p,pc) <= 0 then
                    a := a+1 ;
                end if;
            end if;
        end do:
        a ;
    end proc:
    for n from 1 to 30 do
    for k from A003056(n) to 1 by -1 do
        printf("%4d,",A067627(n,k)) ;
    end do:
    printf("\n") ;
    end do: # R. J. Mathar, May 08 2019

Extensions

More terms from R. J. Mathar, May 08 2019

A067772 One half of the number of non-self-conjugate balanced partitions.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 2, 2, 4, 4, 6, 7, 10, 12, 17, 19, 26, 31, 40, 47, 61, 72, 91, 108, 134, 159, 197, 231, 283, 335, 405, 477, 576, 676, 810, 950, 1131, 1325, 1572, 1834, 2166, 2527, 2970, 3455, 4051, 4702, 5493, 6366, 7412, 8574, 9959, 11493, 13315, 15345, 17729, 20392
Offset: 1

Views

Author

Naohiro Nomoto, Feb 06 2002

Keywords

Crossrefs

Programs

  • PARI
    seq(n) = {my(A=O(x*x^n), m=1); while(3*m^2-m <= 2*n, m++); Vec(1 + sum(k=1, m-1, (-1)^k * ( x^((3*k^2+k)/2) - x^((3*k^2-k)/2) ), A )/eta(x + A) - prod(k=1, (n+1)\2, 1 + x^(2*k-1) + A), -n)/2} \\ Andrew Howroyd, Apr 20 2021

Formula

a(n) = (A047993(n) - A000700(n))/2.
a(n) = A331262(n)/2. - Omar E. Pol, Jun 18 2022

Extensions

Terms a(37) and beyond from Andrew Howroyd, Apr 20 2021

A096648 Number of partitions of an n-set with odd number of even blocks.

Original entry on oeis.org

0, 1, 3, 7, 25, 106, 434, 2045, 10707, 57781, 338195, 2115664, 13796952, 95394573, 692462671, 5235101739, 41436754261, 341177640610, 2915100624274, 25866987547865, 237448494222575, 2252995117706961, 22078799199129799, 222971522853648704, 2319210969809731600
Offset: 1

Views

Author

Vladeta Jovovic, Aug 14 2004

Keywords

Crossrefs

Programs

  • Maple
    with(combinat):
    b:= proc(n, i, t) option remember; `if`(n=0, t, `if`(i<1,
          0, add(multinomial(n, n-i*j, i$j)/j!*b(n-i*j, i-1,
          irem(t+`if`(irem(i, 2)=0, j, 0), 2)), j=0..n/i)))
        end:
    a:= n-> b(n$2, 0):
    seq(a(n), n=1..30);  # Alois P. Heinz, Mar 08 2015
  • Mathematica
    multinomial[n_, k_List] := n!/Times @@ (k!); b[n_, i_, t_] := b[n, i, t] = If[n == 0, t, If[i<1, 0, Sum[multinomial[n, Join[{n-i*j}, Array[i&, j]]]/j!*b[n-i*j, i-1, Mod[t+If[Mod[i, 2] == 0, j, 0], 2]], {j, 0, n/i}]]]; a[n_] := b[n, n, 2]; Table[ a[n], {n, 1, 30}] (* Jean-François Alcover, May 13 2015, after Alois P. Heinz *)
    With[{nn=30},Rest[CoefficientList[Series[Exp[Sinh[x]]Sinh[Cosh[x]-1], {x,0,nn}],x] Range[0,nn]!]] (* Harvey P. Dale, Sep 03 2016 *)

Formula

E.g.f.: exp(sinh(x))*sinh(cosh(x)-1).
a(2*n) = A024429(2*n) and a(2*n+1) = A024430(2*n+1). - Jonathan Vos Post, Oct 19 2005
a(n) = sum{k=0..n, if(mod(n-k,2)=1, A048993(n,k), 0)}. - Paul Barry, May 19 2006

Extensions

More terms from Emeric Deutsch, Nov 16 2004

A353319 Irregular triangle read by rows where T(n,k) is the number of reversed integer partitions of n with k excedances (parts above the diagonal), all zeros removed.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 3, 4, 2, 1, 5, 4, 2, 7, 6, 2, 10, 6, 6, 15, 7, 7, 1, 18, 14, 7, 3, 26, 15, 11, 4, 35, 17, 19, 6, 47, 24, 19, 11, 61, 33, 22, 18, 1, 80, 44, 28, 20, 4, 103, 54, 42, 25, 7, 138, 60, 57, 31, 11, 175, 85, 58, 52, 15, 224, 112, 66, 64, 24
Offset: 1

Views

Author

Gus Wiseman, May 21 2022

Keywords

Examples

			Triangle begins:
   1
   1  1
   2  1
   2  3
   4  2  1
   5  4  2
   7  6  2
  10  6  6
  15  7  7  1
  18 14  7  3
  26 15 11  4
  35 17 19  6
  47 24 19 11
  61 33 22 18  1
  80 44 28 20  4
For example, row n = 9 counts the following reversed partitions:
  (1134)       (9)     (27)   (234)
  (1224)       (18)    (36)
  (1233)       (117)   (45)
  (11115)      (126)   (135)
  (11124)      (1116)  (144)
  (11133)      (1125)  (225)
  (11223)      (2223)  (333)
  (12222)
  (111114)
  (111123)
  (111222)
  (1111113)
  (1111122)
  (11111112)
  (111111111)
		

Crossrefs

Row sums are A000041.
Row lengths are A003056.
The version for permutations is A008292, opposite A123125.
The weak unreversed version is A115720/A115994, rank statistic A257990.
For fixed points instead of excedances we have A238352, rank stat A352822.
Column k = 0 is A238875.
The version for compositions is A352524, weak A352525.
The version for unreversed partitions is A353318.
A000700 counts self-conjugate partitions, ranked by A088902.
A001522 counts partitions with a fixed point, ranked by A352827 (unproved).
A064428 counts partitions w/o a fixed point, ranked by A352826 (unproved).

Programs

  • Mathematica
    partsabove[y_]:=Length[Select[Range[Length[y]],#
    				

A064480 Form a conjugate partition of row with 1+1+1 in first row. all other rows are the union of their parents. a(n) = number of types of piles in the n-th row.

Original entry on oeis.org

1, 2, 3, 5, 7, 10, 13, 19, 26, 36, 51, 69, 94, 130, 188, 261, 366, 514, 710, 993, 1399, 1995, 2779, 3912, 5490, 7723, 10848, 15230, 21457, 30165, 42401, 59718, 83808, 117844, 165932, 233358, 328316, 461885, 650105, 915243, 1287795, 1812815, 2552260, 3593697
Offset: 1

Views

Author

Naohiro Nomoto, Feb 14 2002

Keywords

Comments

The n-th row sum is equal to 3*2^(n-1).
The largest part of the n-th row is A000204(n).

Examples

			Start with 1+1+1 from which a(1)=1.
The conjugate of 1+1+1 is 3, giving the union 3+1+1+1, and a(2)=2.
The conjugate of 3+1+1+1 is 4+1+1, giving the union 4+3+1+1+1+1+1, and a(3)=3.
The conjugate of 4+3+1+1+1+1+1 is 7+2+2+1, giving the union 7+4+3+2+2+1+1+1+1+1+1, and a(4)=5.
		

Crossrefs

Extensions

More terms from Sean A. Irvine, Jul 13 2023

A064660 The number of distinct parts in the partition sequence lambda(n) formed by the recurrence lambda(1) = 1 and lambda(n+1) is the sum of lambda(n) and its conjugate.

Original entry on oeis.org

1, 1, 2, 3, 4, 6, 8, 11, 15, 22, 30, 39, 53, 75, 106, 151, 215, 297, 424, 592, 835, 1162, 1618, 2274, 3217, 4556, 6361, 8940, 12560, 17645, 24822, 34812, 48967, 68861, 96939, 136462, 191896, 269976, 379726, 534239, 751829, 1058170, 1489038, 2096243, 2951262
Offset: 1

Views

Author

Naohiro Nomoto, Feb 14 2002

Keywords

Comments

lambda(n) is a partition of 2^(n-1).
The largest part of lambda(n) is A000045(n).
The number of parts of lambda(n) is A000045(n+1). Peter J. Taylor, Jul 24 2014

Examples

			lambda(4) = 3+2+1+1+1 has conjugate partition 5+2+1, so lambda(5) = 5+3+2+2+1+1+1+1 and a(5) = |{5,3,2,1}| = 4.
		

Crossrefs

Extensions

More terms, description and example rephrased by Peter J. Taylor, Jul 24 2014
Previous Showing 31-40 of 47 results. Next