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 1-2 of 2 results.

A066183 Total sum of squares of parts in all partitions of n.

Original entry on oeis.org

1, 6, 17, 44, 87, 180, 311, 558, 910, 1494, 2302, 3608, 5343, 7986, 11554, 16714, 23549, 33270, 45942, 63506, 86338, 117156, 156899, 209926, 277520, 366260, 479012, 624956, 808935, 1044994, 1340364, 1715572, 2182935, 2770942, 3499379
Offset: 1

Views

Author

Wouter Meeussen, Dec 15 2001

Keywords

Comments

Sum of hook lengths of all boxes in the Ferrers diagrams of all partitions of n (see the Guo-Niu Han paper, p. 25, Corollary 6.5). Example: a(3) = 17 because for the partitions (3), (2,1), (1,1,1) of n=3 the hook length multi-sets are {3,2,1}, {3,1,1}, {3,2,1}, respectively; the total sum of all hook lengths is 6+5+6 = 17. - Emeric Deutsch, May 15 2008
Partial sums of A206440. - Omar E. Pol, Feb 08 2012
Column k=2 of A213191. - Alois P. Heinz, Sep 20 2013
Row sums of triangles A180681, A206561 and A299768. - Omar E. Pol, Mar 20 2018

Examples

			a(3) = 17 because the squares of all partitions of 3 are {9}, {4,1} and {1,1,1}, summing to 17.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; local g, h;
          if n=0 then [1, 0]
        elif i<1 then [0, 0]
        elif i>n then b(n, i-1)
        else g:= b(n, i-1); h:= b(n-i, i);
             [g[1]+h[1], g[2]+h[2] +h[1]*i^2]
          fi
        end:
    a:= n-> b(n, n)[2]:
    seq(a(n), n=1..40);  # Alois P. Heinz, Feb 23 2012
    # second Maple program:
    g := (sum(k^2*x^k/(1-x^k), k = 1..100))/(product(1-x^k, k = 1..100)): gser := series(g, x = 0, 45): seq(coeff(gser, x, m), m = 1 .. 40); # Emeric Deutsch, Dec 06 2015
  • Mathematica
    Table[Apply[Plus, IntegerPartitions[n]^2, {0, 2}], {n, 30}]
    (* Second program: *)
    b[n_, i_] := b[n, i] = Module[{g, h}, Which[n==0, {1, 0}, i<1, {0, 0}, i>n, b[n, i-1], True, g = b[n, i-1]; h = b[n-i, i]; {g[[1]] + h[[1]], g[[2]] + h[[2]] + h[[1]]*i^2}]]; a[n_] :=  b[n, n][[2]]; Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Aug 31 2015, after Alois P. Heinz *)
  • PARI
    a(n)=my(s); forpart(v=n,s+=sum(i=1,#v,v[i]^2));s \\ Charles R Greathouse IV, Aug 31 2015
    
  • PARI
    a(n)=sum(k=1,n,sigma(k,2)*numbpart(n-k)) \\ Charles R Greathouse IV, Aug 31 2015

Formula

a(n) = Sum_{k=1..n} sigma_2(k)*numbpart(n-k), where sigma_2(k)=sum of squares of divisors of k=A001157(k). - Vladeta Jovovic, Jan 26 2002
a(n) = Sum_{k>=0} k*A265245(n,k). - Emeric Deutsch, Dec 06 2015
G.f.: g(x) = (Sum_{k>=1} k^2*x^k/(1-x^k))/Product_{q>=1} (1-x^q). - Emeric Deutsch, Dec 06 2015
a(n) ~ 3*sqrt(2)*Zeta(3)/Pi^3 * exp(Pi*sqrt(2*n/3)) * sqrt(n). - Vaclav Kotesovec, May 28 2018

Extensions

More terms from Naohiro Nomoto, Feb 07 2002

A263003 Partition array for the products of the hook lengths of Ferrers (Young) diagrams corresponding to the partitions of n, written in Abramowitz-Stegun order.

Original entry on oeis.org

1, 1, 2, 2, 6, 3, 6, 24, 8, 12, 8, 24, 120, 30, 24, 20, 24, 30, 120, 720, 144, 80, 144, 72, 45, 144, 72, 80, 144, 720, 5040, 840, 360, 360, 336, 144, 240, 240, 252, 144, 360, 336, 360, 840, 5040, 40320, 5760, 2016, 1440, 2880, 1920, 630, 576, 720, 960, 1152, 448, 720, 576, 2880, 1152, 630, 1440, 1920, 2016, 5760, 40320, 362880, 45360, 13440, 7560, 8640, 12960, 3456, 2240, 4320, 3024, 2160, 8640, 6480, 1920, 1680, 1680, 2160, 4320, 5184, 1920, 3024, 2240, 8640, 6480, 3456, 7560, 12960, 13440, 45360, 362880
Offset: 0

Views

Author

Wolfdieter Lang, Oct 09 2015

Keywords

Comments

The sequence of row lengths is A000041: [1, 1, 2, 3, 5, 7, 11, 15, 22, 30, 42, ...] (partition numbers p(n)).
For the ordering of this tabf array a(n,k) see Abramowitz-Stegun (A-St) ref. pp. 831-2.
This is the array n!/A117506(n,k).
For rows 1..15 of this irregular triangle see the W. Lang link.
The row sums give A263004.
The formula given below is the one obtained from the version given, e.g., in Wybourne's book for A117506(n, k). See also the Glass-Ng reference, Theorem 1, p. 701, which gives the same formula, after rewriting using also a Vandermonde determinant.
In A. Young's third paper (Q.S.A. III, see A117506), Theorem V on p. 266, CP p. 363, f/n! (the present 1/a(n,k)) appears in the decomposition of 1 for each n, that is Sum_{k = 1..p(n)} 1/a(n,k) Sum_{j=1..d(n,k)} Y'(n,k,j) = 1, with d(n,k) = A117506(n,k), and the Young operators Y' for the standard tableaux for the k-th partition of n in A-St order.
a(n,k) also appears as normalization to obtain the idempotents NP/a(n,k). See A. Young, Q.S.A. II, p. 366, CP p. 97: NP = (1/a(n,k)) (NP)^2 for each Young tableau of the shape given by the k-th partition of n in A-St order.

Examples

			The first rows of this irregular triangle are:
n\k   1    2    3    4    5   6    7   8   9   10   11
0:    1
1:    1
2:    2    2
3:    6    3    6
4:   24    8   12    8   24
5:  120   30   24   20   24  30  120
6:  720  144   80  144   72  45  144  72  80  144  720
...
Note that the rows are in general not symmetric.
See the W. Lang link for rows n = 1..15.
a(6,6) is related to the (self-conjugate) partition (1, 2, 3) of n = 6, taken in reverse order (3, 2, 1) with the Ferrers (or Young) diagram
   _ _ _
  |_|_|_| and the hook length numbers   5  3  1 ...
  |_|_|                                 3  1
  |_|                                   1
The product gives 5*3*1*3*1*1 = 45 = a(6,6).
		

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, pp. 831-2.
  • B. Wybourne, Symmetry principles and atomic spectroscopy, Wiley, New York, 1970, p. 9.

Crossrefs

Programs

  • Maple
    h:= l-> (n-> mul(mul(1+l[i]-j+add(`if`(l[k]>=j, 1, 0),
                 k=i+1..n), j=1..l[i]), i=1..n))(nops(l)):
    g:= (n, i, l)->`if`(n=0 or i=1, [h([l[], 1$n])],
                   `if`(i<1, [], [g(n, i-1, l)[],
                   `if`(i>n, [], g(n-i, i, [l[], i]))[]])):
    T:= n-> g(n$2, [])[]:
    seq(T(n), n=0..10);  # Alois P. Heinz, Nov 05 2015

Formula

a(n,k) = Product_{i=1..m(n,k)} (x_i)!/Det(x_i^(m(n,k) - j)) with the Vandermonde determinant for the variables x_i := lambda(n,k)_i + m(n,k) - i, for i, j = 1..m(n,k), where m(n,k) is the number of parts of the k-th partition of n denoted by lambda(n,k), in the A-St order (see above). Lambda(n,k)_i stands for the i-th part of the partition lambda(n,k), sorted in nonincreasing order (this is the reverse of the A-St notation for a partition).

Extensions

Row n=0 prepended by Alois P. Heinz, Nov 05 2015
Showing 1-2 of 2 results.