A102247 Number of partitions of n in which each odd part has odd multiplicity and each even part has even multiplicity.

1, 1, 0, 2, 2, 3, 2, 4, 7, 8, 8, 10, 17, 17, 20, 26, 39, 39, 46, 56, 77, 85, 96, 116, 154, 172, 190, 234, 289, 328, 364, 440, 532, 610, 670, 808, 957, 1091, 1204, 1432, 1675, 1905, 2110, 2476, 2867, 3255, 3608, 4184, 4837, 5451, 6050, 6960, 7980, 8961, 9972, 11370

Offset

0,4

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Formula

G.f.: Product_{i>0} (1+x^(2*i-1)-x^(4*i-2))/(1-x^(2*i)).

a(n) ~ sqrt(Pi^2/3 + 4*log(phi)^2) * exp(sqrt((Pi^2/3 + 4*log(phi)^2)*n)) / (4*Pi*n), where phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Jan 03 2016

Example

a(7) = 4 because we have 7, 322, 22111 and 1111111.

Maple

g:=product((1+x^(2*i-1)-x^(4*i-2))/(1-x^(2*i)), i=1..40): gser:=series(g, x=0, 60): seq(coeff(gser, x, n), n=0..55); # Emeric Deutsch, Aug 23 2007
# second Maple program:
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      add(`if`(irem(i+j, 2)=0, b(n-i*j, i-1), 0), j=1..n/i)
       +b(n, i-1)))
    end:
a:= n-> b(n$2):
seq(a(n), n=0..60);  # Alois P. Heinz, May 31 2014

Mathematica

nmax = 50; CoefficientList[Series[Product[(1 + x^(2*k-1) - x^(4*k-2))/(1-x^(2*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 03 2016 *)

Crossrefs

Cf. A055922, A117958, A130126, A131942, A100847.

Sequence in context: A268327 A053023 A153725 * A054249 A160273 A141822

Adjacent sequences: A102244 A102245 A102246 * A102248 A102249 A102250

Keyword

easy,nonn

Author

Vladeta Jovovic, Aug 16 2007

Extensions

More terms from Emeric Deutsch, Aug 23 2007

Status

approved