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A325876
Number of strict Golomb partitions of n.
13
1, 1, 1, 2, 2, 3, 3, 5, 6, 6, 9, 11, 10, 15, 17, 18, 24, 29, 27, 38, 43, 47, 53, 67, 67, 84, 87, 102, 113, 137, 131, 167, 179, 204, 213, 261, 263, 315, 327, 377, 413, 476, 472, 564, 602, 677, 707, 820, 845, 969, 1027, 1131, 1213, 1364, 1413, 1596, 1700, 1858
OFFSET
0,4
COMMENTS
We define a Golomb partition of n to be an integer partition of n such that every ordered pair of distinct parts has a different difference.
Also the number of strict integer partitions of n such that every orderless pair of (not necessarily distinct) parts has a different sum.
The non-strict case is A325858.
LINKS
Fausto A. C. Cariboni, Table of n, a(n) for n = 0..500
EXAMPLE
The a(2) = 1 through a(11) = 11 partitions (A = 10, B = 11):
(2) (3) (4) (5) (6) (7) (8) (9) (A) (B)
(21) (31) (32) (42) (43) (53) (54) (64) (65)
(41) (51) (52) (62) (63) (73) (74)
(61) (71) (72) (82) (83)
(421) (431) (81) (91) (92)
(521) (621) (532) (A1)
(541) (542)
(631) (632)
(721) (641)
(731)
(821)
MATHEMATICA
Table[Length[Select[IntegerPartitions[n], UnsameQ@@#&&UnsameQ@@Subtract@@@Subsets[Union[#], {2}]&]], {n, 0, 30}]
PROG
(Python)
from collections import Counter
from itertools import combinations
from sympy.utilities.iterables import partitions
def A325876(n): return sum(1 for p in partitions(n) if max(list(Counter(abs(d[0]-d[1]) for d in combinations(list(Counter(p).elements()), 2)).values()), default=1)==1)-(n&1^1) if n else 1 # Chai Wah Wu, Sep 17 2023
CROSSREFS
The subset case is A143823.
The maximal case is A325879.
The integer partition case is A325858.
The strict integer partition case is A325876.
Heinz numbers of the counterexamples are given by A325992.
Sequence in context: A198453 A345162 A316313 * A325468 A320347 A178932
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jun 02 2019
STATUS
approved