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A325358
Number of integer partitions of n whose augmented differences are strictly decreasing.
10
1, 1, 1, 2, 2, 2, 3, 4, 4, 5, 6, 6, 7, 9, 10, 11, 13, 14, 15, 18, 20, 21, 24, 26, 28, 33, 36, 38, 43, 46, 49, 56, 60, 63, 71, 76, 80, 90, 96, 100, 112, 120, 125, 139, 149, 155, 171, 183, 190, 208, 223, 232, 252, 269, 280, 304, 325, 338, 364, 387, 403
OFFSET
0,4
COMMENTS
The augmented differences aug(y) of an integer partition y of length k are given by aug(y)_i = y_i - y_{i + 1} + 1 if i < k and aug(y)_k = y_k. For example, aug(6,5,5,3,3,3) = (2,1,3,1,1,3).
The Heinz numbers of these partitions are given by A325396.
EXAMPLE
The a(1) = 1 through a(11) = 6 partitions:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)
(21) (31) (41) (42) (52) (62) (63) (73) (83)
(51) (61) (71) (72) (82) (92)
(421) (521) (81) (91) (101)
(621) (631) (731)
(721) (821)
MATHEMATICA
aug[y_]:=Table[If[i<Length[y], y[[i]]-y[[i+1]]+1, y[[i]]], {i, Length[y]}];
Table[Length[Select[IntegerPartitions[n], OrderedQ[aug[#], Greater]&]], {n, 0, 30}]
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 01 2019
STATUS
approved