A112761 Exponent of 3 (value of j) in n-th number of the form 2^i*3^j*5^k.

0, 0, 1, 0, 0, 1, 0, 2, 0, 1, 1, 0, 2, 0, 1, 0, 3, 1, 0, 2, 0, 2, 1, 0, 3, 1, 0, 2, 1, 0, 4, 2, 1, 0, 3, 1, 0, 0, 3, 2, 1, 0, 4, 2, 1, 0, 3, 2, 1, 5, 0, 0, 3, 2, 1, 0, 4, 2, 1, 1, 0, 4, 3, 2, 1, 5, 0, 0, 3, 2, 1, 0, 0, 4, 3, 2, 6, 1, 1, 0, 4, 3, 2, 1, 5, 0, 0, 3, 2, 2, 1, 5, 0, 0, 4, 3, 2, 6, 1, 1, 0, 4, 3, 2, 1

Offset: 1

Author

Reinhard Zumkeller, Sep 18 2005

Keywords

• nonn

Links

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

Crossrefs

Cf. A007949, A022336, A022329, A051037, A112759, A112760, A112762.

Programs

Mathematica

IntegerExponent[#, 3] & /@ Select[Range[3000], Last @ Map[First, FactorInteger[#]] <= 5 &] (* Amiram Eldar, Feb 07 2020 *)

Formula

a(n) = A007949(A051037(n));

a(n) = A112759(n) - A112760(n) - A112762(n).