The cumulative partition function is the partial sum
where
is the partition function and
(Ji 2026). For
, 2, ..., its values are 1, 2, 4, 7, 12, 19, 30, 45, 67,
97, ... (OEIS A000070, shifted by one place).
Ji (2026) proved that for every integer ,
, and
, the sequence
is not eventually constant modulo
, and consequently is not eventually periodic modulo
. In particular, both parities occur
infinitely often on every arithmetic progression.
This does not assert that every residue modulo
occurs.