OFFSET
0,2
COMMENTS
Note the indexing: the domain starts from 0, while the range excludes zero.
From Antti Karttunen, Jul 25 2016: (Start)
This sequence can be represented as a binary tree. Each left hand child is obtained by applying A016789(n-1) when the parent contains n (i.e., multiply by 3, subtract one), and each right hand child is obtained by applying A254049 to the parent's contents:
1
|
...................2...................
5 3
14......../ \........13 8......../ \........4
/ \ / \ / \ / \
/ \ / \ / \ / \
/ \ / \ / \ / \
41 63 38 25 23 18 11 6
122 313 188 172 113 123 74 61 68 88 53 39 32 28 17 7
etc.
(End)
LINKS
FORMULA
a(0) = 1, a(1) = 2, a(2n) = 3*a(n)-1, a(2n+1) = A254049(a(n)). - Antti Karttunen, Jul 25 2016
MATHEMATICA
Table[(Times @@ Power[If[# == 1, 1, NextPrime@ #] & /@ First@ #, Last@ #] + 1)/2 &@ Transpose@ FactorInteger@ If[n == 0, 1, Prime[#] Product[Prime[m]^(Map[Ceiling[(Length@ # - 1)/2] &, DeleteCases[Split@ Join[Riffle[IntegerDigits[n, 2], 0], {0}], {k__} /; k == 1]][[-m]]), {m, #}] &[DigitCount[n, 2, 1]]], {n, 0, 63}] (* Michael De Vlieger, Jul 25 2016 *)
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Antti Karttunen, Jul 28 2014
STATUS
approved