A025652 Exponent of 5 (value of i) in n-th number of form 5^i*7^j.

0, 1, 0, 2, 1, 0, 3, 2, 1, 0, 4, 3, 2, 1, 0, 5, 4, 3, 2, 1, 6, 0, 5, 4, 3, 2, 7, 1, 6, 0, 5, 4, 3, 8, 2, 7, 1, 6, 0, 5, 4, 9, 3, 8, 2, 7, 1, 6, 0, 5, 10, 4, 9, 3, 8, 2, 7, 1, 6, 0, 11, 5, 10, 4, 9, 3, 8, 2, 7, 1, 12, 6, 0, 11, 5, 10, 4, 9, 3, 8, 2, 13, 7, 1, 12, 6, 0, 11, 5, 10, 4, 9, 3, 14, 8, 2, 13, 7, 1, 12, 6

Offset

1,4

Links

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

Formula

a(n) = A112765(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, 5]; seq[10^11] (* Amiram Eldar, Nov 08 2025 *)

Crossrefs

Cf. A003595, A025667, A112765.

Sequence in context: A025646 A025661 A025671 * A025662 A025640 A025663

Adjacent sequences: A025649 A025650 A025651 * A025653 A025654 A025655

Keyword

nonn,easy

Author

David W. Wilson

Status

approved