A025667 Exponent of 7 (value of j) in n-th number of form 5^i*7^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, 9, 0, 5, 1, 6, 2, 7, 3, 8, 4, 9, 0, 5, 10, 1, 6, 2, 7, 3, 8, 4, 9, 0, 5, 10, 1, 6, 11, 2, 7, 3, 8, 4, 9, 0, 5, 10, 1, 6, 11, 2, 7, 12, 3, 8, 4

Offset

1,6

Links

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

Formula

a(n) = A214411(A003595(n)). - Amiram Eldar, Nov 08 2025

Mathematica

seq[lim_] := IntegerExponent[Flatten[Table[5^i*7^j, {i, 0, Log[5, lim]}, {j, 0, Log[7, lim/5^i]}]] // Sort, 7]; seq[10^11] (* Amiram Eldar, Nov 08 2025 *)

Crossrefs

Cf. A003595, A025652, A214411.

Sequence in context: A025645 A233381 A025680 * A025689 A025650 A025674

Adjacent sequences: A025664 A025665 A025666 * A025668 A025669 A025670

Keyword

nonn,easy

Author

David W. Wilson

Status

approved