A068191 Numbers n such that A067734(n)=0; complement of A002473; at least one prime-factor of n is larger than 7, it has 2 decimal digits.

11, 13, 17, 19, 22, 23, 26, 29, 31, 33, 34, 37, 38, 39, 41, 43, 44, 46, 47, 51, 52, 53, 55, 57, 58, 59, 61, 62, 65, 66, 67, 68, 69, 71, 73, 74, 76, 77, 78, 79, 82, 83, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 97, 99, 101, 102, 103, 104, 106, 107, 109, 110, 111, 113, 114

Offset

1,1

Comments

Also numbers n such that A198487(n) = 0 and A107698(n) = 0. - Jaroslav Krizek, Nov 04 2011

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

Cf. A001222, A002473, A067734.

Cf. A068183, A068184, A068185, A068186, A068187, A068189, A068190.

Cf. A262401.

Sequence in context: A061116 A333237 A048388 * A376740 A191599 A084374

Adjacent sequences: A068188 A068189 A068190 * A068192 A068193 A068194

Keyword

base,nonn

Author

Labos Elemer, Feb 19 2002

Status

approved