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A036052
Product of the lengths of the cycle types of the permutation created by length sorting on the partitions of n.
1
1, 1, 1, 1, 2, 2, 6, 10, 60, 144, 348, 8526, 8930, 322560, 210540, 7296, 7001280, 3325069440, 176880000, 44528400, 6398154000, 74839427712000, 222108480000, 52321920, 1864464000, 5066300010240, 1338148188, 91406407293961987500
OFFSET
0,5
PROG
(PARI)
OrderCycs(v)={my(t=vector(#v), L=List()); for(i=1, #v, my(c=0, j=i); while(!t[j], t[j]=1; j=v[j]; c++); if(c, listput(L, c))); Vec(L)}
a(n)={my(u=vecsort([Vecsmall(Vecrev(p)) | p<-partitions(n)])); my(v=vecsort(u, (x, y)->lex(#x, #y), 1+4)); vecprod(Set(OrderCycs(v)))} \\ Andrew Howroyd, Sep 17 2019
CROSSREFS
KEYWORD
nonn
EXTENSIONS
Name changed to agree with data and a(0)=1 prepended by Andrew Howroyd, Sep 17 2019
STATUS
approved