A189822 Positions of 1 in A189820; complement of A003278.

3, 6, 7, 8, 9, 12, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 30, 33, 34, 35, 36, 39, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 84

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..10000

Mathematica

a[1] = 0; h = 50;
Table[a[3 k - 2] = a[k], {k, 1, h}];
Table[a[3 k - 1] = a[k], {k, 1, h}];
Table[a[3 k] = 1, {k, 1, h}];
Flatten[Position[%%, 1]]

Prog

(Python)
from gmpy2 import digits
def A189822(n):
    def f(x):
        l = (s:=digits(x-1, 3)).find('2')
        if l >= 0: s = s[:l]+'1'*(len(s)-l)
        return n+1+int(s, 2)
    m, k = n, f(n)
    while m != k: m, k = k, f(k)
    return m # Chai Wah Wu, Dec 05 2024

Crossrefs

Cf. A081610, A189820, A003278.

Sequence in context: A113826 A376588 A053030 * A051205 A168114 A220656

Adjacent sequences: A189819 A189820 A189821 * A189823 A189824 A189825

Keyword

nonn,easy,changed

Author

Clark Kimberling, Apr 28 2011

Status

approved