OFFSET
1,2
COMMENTS
REFERENCES
G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976, pp. 179-201.
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: g(x) = Sum_{j>=1} (j*x^j/(1-x^j))/Product_{k>=1} (1-x^k)^k.
a(n) = Sum(k*A089353(n,k), k>=1).
EXAMPLE
a(3) = 10 because the 6 (=A000219(3)) planar partitions of 3 are [3], [2,1], [2;1], [1,1,1], [1;1;1], [1,1;1] (; indicates a new row); the sum of their traces is 3+2+2+1+1+1 = 10.
MAPLE
g:= (sum(j*x^j/(1-x^j), j = 1..100))/(product((1-x^k)^k, k = 1..100)): gser := series(g, x = 0, 40): seq(coeff(gser, x, m), m = 1 .. 35);
# second Maple program:
b:= proc(n, i) option remember; `if`(n=0, [1, 0], `if`(i<1, 0, add((p
->p+[0, j*p[1]])(b(n-i*j, i-1))*binomial(i+j-1, j), j=0..n/i)))
end:
a:= n-> b(n$2)[2]:
seq(a(n), n=1..50); # Alois P. Heinz, Sep 24 2018
MATHEMATICA
nmax = 50; Rest[CoefficientList[Series[Sum[j*x^j/(1-x^j), {j, 1, nmax}]*Product[1/(1-x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Sep 25 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Emeric Deutsch, Sep 24 2016
STATUS
approved