OFFSET
1,2
COMMENTS
FORMULA
EXAMPLE
MATHEMATICA
f[1, n_] := 2^n; f[2, n_] := 3^n;
f[3, n_] := 5^n; z = 1000;
d[n_, b_, c_] := Floor[n*Log[b, c]];
t[k_] := Table[f[k, n], {n, 1, z}];
t = Sort[Union[t[1], t[2], t[3]]];
p[k_, n_] := Position[t, f[k, n]];
Flatten[Table[p[1, n], {n, 1, z/8}]] (* A206812 *)
Table[n + d[n, 3, 2] + d[n, 5, 2],
{n, 1, 50}] (* A206812 *)
Flatten[Table[p[2, n], {n, 1, z/8}]] (* A206813 *)
Table[n + d[n, 2, 3] + d[n, 5, 3],
{n, 1, 50}] (* A206813 *)
Flatten[Table[p[3, n], {n, 1, z/8}]] (* A206814 *)
Table[n + d[n, 2, 5] + d[n, 3, 5],
{n, 1, 50}] (* A206814 *)
PROG
(PARI) a(n) = n + logint(2^n, 3) + logint(2^n, 5) \\ Ruud H.G. van Tol, Nov 16 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Feb 17 2012
STATUS
approved