OFFSET
1,2
COMMENTS
The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..20000
MAPLE
a:= proc(n) option remember; local k; for k from 1+`if`(n=1,
0, a(n-1)) while add(`if`(numtheory[pi](i[1])::odd,
0, i[2]), i=ifactors(k)[2])::odd do od; k
end:
seq(a(n), n=1..100); # Alois P. Heinz, Nov 24 2018
MATHEMATICA
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[200], EvenQ[Count[primeMS[#], _?EvenQ]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 24 2018
STATUS
approved