|
Search: id:A118306
|
|
|
| A118306 |
|
If n = product(k>=1} p(k)^b(n,k), where p(k) is the k-th prime and where each b(n,k) is a nonnegative integer, then: If n occurs earlier in the sequence, then a(n) = product{k>=2} p(k-1)^b(n,k); If n does not occur earlier in the sequence, then a(n) = {k>=1} p(k+1)^b(n,k). |
|
+0
2
|
|
| 1, 3, 2, 9, 7, 15, 5, 27, 4, 21, 13, 45, 11, 33, 6, 81, 19, 75, 17, 63, 10, 39, 29, 135, 49, 51, 8, 99, 23, 105, 37, 243, 14, 57, 77, 225, 31, 69, 22, 189, 43, 165, 41, 117, 12, 87, 53, 405, 25, 147, 26, 153, 47, 375, 91, 297, 34, 93, 61, 315, 59, 111, 20, 729, 119, 195, 71
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Sequence is a permutation of the positive integers and it is its own inverse permutation.
|
|
LINKS
|
Leroy Quet, Home Page (listed in lieu of email address)
|
|
MAPLE
|
A064989 := proc(n) local a, ifs, p ; a := 1 ; ifs := ifactors(n)[2] ; for p in ifs do if op(1, p) > 2 then a := a* prevprime(op(1, p))^op(2, p) ; fi ; od; RETURN(a) ; end: A003961 := proc(n) local a, ifs, p ; a := 1 ; ifs := ifactors(n)[2] ; for p in ifs do a := a* nextprime(op(1, p))^op(2, p) ; od; RETURN(a) ; end: A118306 := proc(nmin) local a, anxt, i, n ; a := [1] ; while nops(a) < nmin do n := nops(a)+1 ; if n in a then anxt := A064989(n) ; else anxt := A003961(n) ; fi ; a := [op(a), anxt] ; od; a ; end: A118306(100) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 06 2007
|
|
CROSSREFS
|
Cf. A003961, A064989.
Sequence in context: A061898 A021756 A084398 this_sequence A124003 A159588 A118045
Adjacent sequences: A118303 A118304 A118305 this_sequence A118307 A118308 A118309
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet May 14 2006
|
|
EXTENSIONS
|
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 06 2007
|
|
|
Search completed in 0.002 seconds
|
