A025685 - OEIS

A025685

Exponent of 10 (value of j) in n-th number of form 3^i*10^j.

0, 0, 0, 1, 0, 1, 0, 1, 2, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 0, 1, 2, 3, 4, 5, 6, 0, 1, 2, 3, 4, 5, 6, 7, 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, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7

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OFFSET

1,9

COMMENTS

Different from A055087, since a(143) = 0 and a(144) = 11.

LINKS

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

FORMULA

a(n) = A007814(A025616(n)). - R. J. Mathar, Feb 26 2024

a(n) = A112765(A025616(n)) = A122840(A025616(n)). - Amiram Eldar, Nov 09 2025

MATHEMATICA

seq[lim_] := IntegerExponent[Flatten[Table[3^i*10^j, {i, 0, Log[3, lim]}, {j, 0, Log10[lim/3^i]}]] // Sort, 10]; seq[10^10] (* Amiram Eldar, Nov 09 2025 *)

CROSSREFS

Cf. A007814, A025616, A025644, A055087, A112765.

Sequence in context: A129714 A022333 A055087 * A194515 A163325 A105186

Adjacent sequences: A025682 A025683 A025684 * A025686 A025687 A025688

KEYWORD

nonn,easy

AUTHOR

David W. Wilson

STATUS

approved