A191291 The number of bases >=2 in which n is 3-digit number.

0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5

Offset

1,16

Links

Table of n, a(n) for n=1..82.

Formula

a(n) = floor(sqrt(n))-floor(n^(1/3)) = A000196(n) - A048766(n).

Mathematica

Table[Floor[Sqrt[n]]-Floor[CubeRoot[n]], {n, 90}] (* Harvey P. Dale, Mar 22 2023 *)

Prog

(PARI) a(n)=sqrtint(n)-floor((n+.5)^(1/3)) \\ Charles R Greathouse IV, Jan 03 2013

Crossrefs

Cf. A191279.

Sequence in context: A328680 A256707 A151963 * A131841 A309432 A230261

Adjacent sequences: A191288 A191289 A191290 * A191292 A191293 A191294

Keyword

nonn,easy,base

Author

Vladimir Shevelev, May 29 2011

Status

approved