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

Author

Vladimir Shevelev, May 29 2011

Keywords

• nonn
• easy
• base

Crossrefs

Cf. A191279.

Programs

Mathematica

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

PARI

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

Formula

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