OFFSET
0,4
FORMULA
EXAMPLE
Non-isomorphic representatives of the a(2) = 1 through a(5) = 16 multiset partitions:
{{1}} {{12}} {{1222}} {{12333}}
{{1}{2}} {{1}{222}} {{1}{2333}}
{{12}{22}} {{12}{333}}
{{2}{122}} {{13}{233}}
{{1}{2}{22}} {{3}{1233}}
{{2}{2}{12}} {{33}{123}}
{{1}{2}{2}{2}} {{1}{2}{333}}
{{1}{23}{33}}
{{1}{3}{233}}
{{3}{12}{33}}
{{3}{13}{23}}
{{3}{3}{123}}
{{1}{1}{1}{23}}
{{1}{2}{3}{33}}
{{1}{3}{3}{23}}
{{1}{2}{3}{3}{3}}
PROG
(PARI) \\ Requires C(sig) from A318285.
a(n)={if(n<2, 1, my(f=factor(n!)[, 2], sig=vector(vecmax(f))); for(i=1, #f, sig[f[i]]++); C(sig))} \\ Andrew Howroyd, Jan 17 2023
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, May 08 2019
EXTENSIONS
a(9)-a(17) from Andrew Howroyd, Jan 17 2023
STATUS
approved