OFFSET
1,2
COMMENTS
a(n) is divisible by 4 for n >= 4. - Eric M. Schmidt, Apr 28 2013
REFERENCES
John McKay, Irreducible representations of odd degree, Journal of Algebra 20, 1972 pages 416-418.
LINKS
Eric M. Schmidt, Table of n, a(n) for n = 1..200
Eric M. Schmidt, Sage code to compute this sequence
FORMULA
a(2^n) = 2^(2^n - 1). - Eric M. Schmidt, Apr 28 2013
MATHEMATICA
h[l_] := With[{n = Length[l]}, Total[l]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i + 1, n}], {j, 1, l[[i]]}], {i, 1, n}]];
g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Array[1 &, n]]], If[i < 1, 0, Flatten@ Table[g[n - i*j, i - 1, Join[l, Array[i &, j]]], {j, 0, n/i}]]];
a[n_] := a[n] = If[n == 1, 1, Select[g[n, n, {}], OddQ] // Total];
Table[Print[n, " ", a[n]];
PROG
(Sage)
# Simple but inefficient; see links for faster code
def A089248(n) :
res = 0
for P in Partitions(n) :
deg = P.dimension()
if is_odd(deg) : res += deg
return res
# Eric M. Schmidt, Apr 28 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Yuval Dekel (dekelyuval(AT)hotmail.com), Dec 11 2003
EXTENSIONS
More terms from Eric M. Schmidt, Apr 28 2013
STATUS
approved