OFFSET
1,1
COMMENTS
a(n) is the least positive integer k such that (1 + n/100)^k >= 2.
LINKS
Wikipedia, Rule of 72
FORMULA
a(n) = 1 for n >= 100.
EXAMPLE
n | a(n) | Rule of 72 (= 72/n)
------+------+---------------------
1 | 70 | 72
2 | 36 | 36
3 | 24 | 24
4 | 18 | 18
5 | 15 | 14.4
6 | 12 | 12
7 | 11 | 10.285714...
8 | 10 | 9
9 | 9 | 8
10 | 8 | 7.2
11 | 7 | 6.545454...
12 | 7 | 6
MAPLE
seq(ceil(log(2)/(log(1+n/100))), n=1..100); # Muniru A Asiru, Aug 30 2018
MATHEMATICA
Table[Ceiling[Log[2]/Log[1 + n/100]], {n, 100}] (* Vincenzo Librandi, Sep 01 2018 *)
PROG
(PARI) {a(n) = ceil(log(2)/(log(1+n/100)))}
(Magma) [Ceiling(Log(2)/(Log(1+n/100))): n in [1..100]]; // Vincenzo Librandi, Sep 01 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 29 2018
STATUS
approved