OFFSET
1,2
COMMENTS
Number of ways to choose a constant integer partition of each part of a constant integer partition of 2^(n - 1).
EXAMPLE
The a(1) = 1 through a(4) = 30 twice-partitions:
(1) (2) (4) (8)
(11) (22) (44)
(1)(1) (1111) (2222)
(2)(2) (4)(4)
(11)(2) (22)(4)
(2)(11) (4)(22)
(11)(11) (22)(22)
(1)(1)(1)(1) (1111)(4)
(4)(1111)
(11111111)
(1111)(22)
(22)(1111)
(1111)(1111)
(2)(2)(2)(2)
(11)(2)(2)(2)
(2)(11)(2)(2)
(2)(2)(11)(2)
(2)(2)(2)(11)
(11)(11)(2)(2)
(11)(2)(11)(2)
(11)(2)(2)(11)
(2)(11)(11)(2)
(2)(11)(2)(11)
(2)(2)(11)(11)
(11)(11)(11)(2)
(11)(11)(2)(11)
(11)(2)(11)(11)
(2)(11)(11)(11)
(11)(11)(11)(11)
(1)(1)(1)(1)(1)(1)(1)(1)
MATHEMATICA
Table[Sum[k^2^(n-k), {k, n}], {n, 12}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 27 2019
STATUS
approved