|
Search: id:A067587
|
|
|
| A067587 |
|
Inverse of A066884 considered as a permutation of the positive integers. |
|
+0
3
|
|
| 1, 3, 2, 6, 5, 9, 4, 10, 14, 20, 8, 27, 13, 19, 7, 15, 35, 44, 26, 54, 34, 43, 12, 65, 53, 64, 18, 76, 25, 33, 11, 21, 77, 90, 89, 104, 103, 118, 42, 119, 134, 151, 52, 169, 63, 75, 17, 135, 188, 208, 88, 229, 102, 117, 24, 251, 133, 150, 32, 168, 41, 51, 16, 28, 152
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
FORMULA
|
Let w(n)=A000120(n) be the 'weight' of n; i.e. the number of 1's in the binary expansion of n. Let p(n)=A068076(n) be the number of positive integers < n with the same weight as n. Then a(n) = binomial(w(n)+p(n), 2) + p(n) + 1.
|
|
MATHEMATICA
|
w[n_] := Plus@@IntegerDigits[n, 2]; p[n_] := Plus@@MapThread[Binomial, {Flatten[Position[Reverse[IntegerDigits[n, 2]], 1]]-1, Range[w[n]]}]; a[n_] := Binomial[w[n]+p[n], 2]+p[n]+1
|
|
CROSSREFS
|
Sequence in context: A133729 A118833 A046877 this_sequence A120476 A069159 A085179
Adjacent sequences: A067584 A067585 A067586 this_sequence A067588 A067589 A067590
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Jared Ricks (jaredricks(AT)yahoo.com), Jan 31 2002
|
|
EXTENSIONS
|
Edited by Dean Hickerson (dean(AT)math.ucdavis.edu), Feb 16 2002
|
|
|
Search completed in 0.002 seconds
|
