A025682 Exponent of 9 (value of j) in n-th number of form 8^i*9^j.

0, 0, 1, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Offset

1,6

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A007949(A025633(n))/2. - Amiram Eldar, Nov 09 2025

Mathematica

seq[lim_] := IntegerExponent[Flatten[Table[8^i*9^j, {i, 0, Log[8, lim]}, {j, 0, Log[9, lim/8^i]}]] // Sort, 9]; seq[10^13] (* Amiram Eldar, Nov 09 2025 *)

Crossrefs

Cf. A007949, A025633, A025676.

Differs from A002262 at a(190).

Sequence in context: A373748 A048151 A025675 * A025691 A002262 A374448

Adjacent sequences: A025679 A025680 A025681 * A025683 A025684 A025685

Keyword

nonn,easy

Author

David W. Wilson

Status

approved