OFFSET
1,2
COMMENTS
LINKS
Jinyuan Wang, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = n + floor(n*log_2(3)) (while A206807(n) = n + floor(n*log_3(2))).
EXAMPLE
The joint ranking begins with 2,3,4,8,9,16,27,32,64,81,128,243,256, so that
this sequence = (1,3,4,6,8,9,11,13,...),
A206807 = (2,5,7,10,12,...).
MATHEMATICA
f[n_] := 2^n; g[n_] := 3^n; z = 200;
c = Table[f[n], {n, 1, z}]; s = Table[g[n], {n, 1, z}];
j = Sort[Union[c, s]];
p[n_] := Position[j, f[n]]; q[n_] := Position[j, g[n]];
Flatten[Table[p[n], {n, 1, z}]] (* A206805 *)
Table[n + Floor[n*Log[3, 2]], {n, 1, 50}] (* A206805 *)
Flatten[Table[q[n], {n, 1, z}]] (* A206807 *)
Table[n + Floor[n*Log[2, 3]], {n, 1, 50}] (* A206807 *)
PROG
(PARI) a(n) = n + floor(n*log(2)/log(3)); \\ Jinyuan Wang, Jan 27 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Feb 16 2012
STATUS
approved