|
| |
|
|
A214411
|
|
The maximum exponent k of 7 such that 7^k divides n.
|
|
13
|
|
|
|
0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,49
|
|
|
COMMENTS
|
7-adic valuation of n.
|
|
|
LINKS
|
Harvey P. Dale, Table of n, a(n) for n = 1..1000
|
|
|
FORMULA
|
G.f.: Sum_{k>=1} x^(7^k)/(1-x^(7^k)). See A112765. - Wolfdieter Lang, Jun 18 2014
If n == 0 (mod 7) then a(n) = 1 + a(n/7), otherwise a(n) = 0. - M. F. Hasler, Mar 05 2020
|
|
|
EXAMPLE
|
n=147 = 3*7*7 is divisible by 7^2, so a(147)=2.
|
|
|
MAPLE
|
seq(padic:-ordp(n, 7), n=1..100); # Robert Israel, Mar 05 2020
|
|
|
MATHEMATICA
|
mek[n_]:=Module[{k=Ceiling[Log[7, n]]}, While[!Divisible[n, 7^k], k--]; k]; Array[ mek, 140] (* Harvey P. Dale, Mar 27 2017 *)
IntegerExponent[Range[150], 7] (* Suggested by Amiram Eldar *) (* Harvey P. Dale, Mar 07 2020 *)
|
|
|
PROG
|
(PARI) a(n)=valuation(n, 7) \\ Charles R Greathouse IV, Jul 17 2012
(PARI) A=vector(1000); for(i=1, log(#A+.5)\log(7), forstep(j=7^i, #A, 7^i, A[j]++)); A \\ Charles R Greathouse IV, Jul 17 2012
|
|
|
CROSSREFS
|
Cf. A007814 (2-adic), A007949 (3-adic), A112765 (5-adic), A082784.
Sequence in context: A280618 A089807 A089810 * A324179 A216577 A096562
Adjacent sequences: A214408 A214409 A214410 * A214412 A214413 A214414
|
|
|
KEYWORD
|
nonn,easy
|
|
|
AUTHOR
|
Redjan Shabani, Jul 16 2012
|
|
|
STATUS
|
approved
|
| |
|
|
