A025680 Exponent of 9 (value of j) in n-th number of form 6^i*9^j.

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

Offset

1,6

Links

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

Formula

a(n) = A007949(A025628(n)/6^A025662(n))/2. - Amiram Eldar, Nov 09 2025

Mathematica

seq[lim_] := SortBy[Flatten[Table[{i, j}, {i, 0, Log[6, lim]}, {j, 0, Log[9, lim/6^i]}], 1], 6^#[[1]]*9^#[[2]] &][[;; , 2]]; seq[10^12] (* Amiram Eldar, Nov 09 2025 *)

Crossrefs

Cf. A025628, A025662.

Sequence in context: A025688 A025645 A233381 * A025667 A025689 A025650

Adjacent sequences: A025677 A025678 A025679 * A025681 A025682 A025683

Keyword

nonn,easy

Author

David W. Wilson

Status

approved