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A035399
Limit of the position of the n-th partition without repetition in the list of all integer partitions sorted in reverse lexicographic order.
5
1, 2, 3, 5, 6, 8, 9, 13, 14, 15, 20, 21, 22, 25, 31, 32, 33, 35, 36, 46, 47, 48, 50, 51, 54, 68, 69, 70, 72, 73, 75, 76, 81, 98, 99, 100, 102, 103, 105, 106, 111, 112, 120, 140, 141, 142, 144, 145, 147, 148, 152, 153, 154, 160, 163, 196, 197, 198, 200, 201, 203
OFFSET
1,2
EXAMPLE
For i=5, the partitions of i are 5, 41, 32, 311, 221, 2111, 11111.
The partitions without repetition are at position 1,2 and 3, corresponding to the first three terms of the sequence.
For i=10, the partitions of i begin 10, 91, 82, 811, 73, 721, 7111, 64, 631, 622, ...
The partitions without repetition are at position 1,2,3,5,6,8,9, ...
MATHEMATICA
it=Table[Flatten[Position[IntegerPartitions[n], q_List/; Sort[q]==Union[q] , 1]], {n, 36, 36+2, 2}];
{{diffat}}=Position[Take[Last[it], Length[First[it] ] ] - First[it] , a_ /; (a!=0), 1, 1]; Take[First[it], diffat -1 ]
CROSSREFS
KEYWORD
nonn
EXTENSIONS
Example and explanations from Olivier Gérard, Feb 13 2011
STATUS
approved