OFFSET
1,1
COMMENTS
A086299(a(n)) = 0. - Reinhard Zumkeller, Apr 01 2012
A262401(a(n)) < a(n). - Reinhard Zumkeller, Sep 25 2015
Numbers not in A007954. - Mohammed Yaseen, Sep 13 2022
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range@120, Last@Map[First, FactorInteger@#] > 7 &] (* Vincenzo Librandi, Sep 19 2016 *)
PROG
(Haskell)
import Data.List (elemIndices)
a068191 n = a068191_list !! (n-1)
a068191_list = map (+ 1) $ elemIndices 0 a086299_list
-- Reinhard Zumkeller, Apr 01 2012
(Python)
from sympy import integer_log
def A068191(n):
def f(x):
c = n
for i in range(integer_log(x, 7)[0]+1):
i7 = 7**i
m = x//i7
for j in range(integer_log(m, 5)[0]+1):
j5 = 5**j
r = m//j5
for k in range(integer_log(r, 3)[0]+1):
c += (r//3**k).bit_length()
return c
m, k = n, f(n)
while m != k: m, k = k, f(k)
return m # Chai Wah Wu, Sep 16 2024
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Labos Elemer, Feb 19 2002
STATUS
approved