A025672 Exponent of 8 (value of j) in n-th number of form 3^i*8^j.

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

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Sean A. Irvine, Table of n, a(n) for n = 1..10000
• Sean A. Irvine, Table of n, a(n) for n = 1..981730 [a large file]
• OEIS server, Scatterplot of n, a(n) with n=1..10^6.

Programs

PARI

A025672(n)=valuation(A025615(n),8) \\ M. F. Hasler, Feb 20 2012

PARI

for(n=1,1e9,n==8^valuation(n,8)*3^valuation(n,3)&&print1(valuation(n,8),", ")) \\ M. F. Hasler, Feb 20 2012

Formula

a(n) = valuation(A025615(n),8) = valuation(A025615(n),2)/3 = A007814(A025615(n))/3. - M. F. Hasler, Feb 20 2012

Extensions

Incorrect formula deleted by Sean A. Irvine, Feb 20 2012