login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A025666 Exponent of 7 (value of j) in n-th number of form 4^i*7^j. 1
0, 0, 1, 0, 1, 2, 0, 1, 2, 0, 3, 1, 2, 0, 3, 1, 4, 2, 0, 3, 1, 4, 2, 0, 5, 3, 1, 4, 2, 0, 5, 3, 1, 6, 4, 2, 0, 5, 3, 1, 6, 4, 2, 7, 0, 5, 3, 1, 6, 4, 2, 7, 0, 5, 3, 8, 1, 6, 4, 2, 7, 0, 5, 3, 8, 1, 6, 4, 9, 2, 7, 0, 5, 3, 8, 1, 6, 4, 9, 2, 7, 0, 5, 10, 3, 8, 1, 6, 4, 9, 2, 7, 0, 5, 10, 3, 8, 1, 6, 11, 4, 9, 2, 7, 0, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

4^A025648(n)*7^a(n) = A025619(n). - Robert Israel, Aug 11 2019

MAPLE

N:= 10^10: # to consider all terms with 4^i*7^j<=N

S:= {seq(seq(4^i*7^j, j=0..floor(log[7](N/4^i))), i=0..floor(log[4](N)))}:

map(padic:-ordp, sort(convert(S, list)), 7); # Robert Israel, Aug 11 2019

CROSSREFS

Cf. A025619, A025648.

Sequence in context: A173863 A022337 A025687 * A025679 A071491 A156537

Adjacent sequences:  A025663 A025664 A025665 * A025667 A025668 A025669

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 22 20:09 EDT 2020. Contains 337291 sequences. (Running on oeis4.)