A390765 Number of digits in base-7 representation of n.

1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3

Offset

0,8

Links

Paolo Xausa, Table of n, a(n) for n = 0..10000

Formula

a(n) = floor(log_7(n)) + 1, for n >= 1.

Example

a(1000) = 4 because 1000 = 2626_7 (4 digits).

Mathematica

A390765[n_] := If[n == 0, 1, IntegerLength[n, 7]];
Array[A390765, 100, 0]

Crossrefs

Cf. analogous sequences for other bases: A070939 (base 2), A081604 (base 3), A110591 (base 4), A110592 (base 5), A390764 (base 6), A390766 (base 8), A390767 (base 9), A055642 (base 10).

Cf. A007093.

Sequence in context: A071702 A225541 A355480 * A076303 A339276 A343356

Adjacent sequences: A390762 A390763 A390764 * A390766 A390767 A390768

Keyword

nonn,base,easy

Author

Paolo Xausa, Nov 18 2025

Status

approved