The nature of the code given in the following examples is explained in the index document.
Integer sequences which are calculated directly from their indexes
can in turn have that calculation applied over and over again.
Here such a sequence of such results is called a chain,
and any stage of the chain of results is called a link.
Base Functions
Functions to be used as a basis for the secondary functions defined
below are given with explanation and examples in the
index file, so their definitions are simply
listed in the following.
spf =: +/@q: NB. sum of prime factors
snpf =: +/@~.@q: NB. sum of nub of prime factors
sopf =: +/@(1&,)@q: NB. sum of one and prime factors
sonpf =: +/@(1&,)@~.@q: NB. sum of one and nub of prime factors