\(B_n\) counts partitions of an \(n\)-set into any number of
blocks, so \(B_n = \sum_k S(n,k)\). The triangle is used instead of
that sum because it needs only additions.
Arguments
- n
Non-negative whole number.
Details
\(B_{25} = 4638590332229999353\), past the exact range of a double,
which is why this returns a morie_bigint.
References
Stanley RP (2011) vol. 1, Sec 1.9.
Examples
morie_bell_number(n = 5L)
#> 52
