A392782 Complement of A000792.

5, 7, 8, 10, 11, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77

Offset

1,1

Comments

Numbers not of the form 3^k, 2*3^k, 4*3^k.

Links

Table of n, a(n) for n=1..66.

Formula

For n>=12, a(n) = n+m+1 if n+m>=A000792(m+1) and a(n) = n+m otherwise where m = A349983(n).

Mathematica

Select[Range[77], Or[Divisible[#, 8], FactorInteger[#][[-1, 1]] > 3] &] (* Michael De Vlieger, Jan 24 2026 *)

Prog

(Python)
from sympy import integer_log
def A000792(n):
    q, r = divmod(n, 3)
    return int((3, 4, 6)[r]*3**(q-1))
def A392782(n):
    if n<12: return (5, 7, 8, 10, 11, 13, 14, 15, 16, 17, 19)[n-1]
    def f(x): return 3+integer_log(x, 3)[0]+integer_log(x>>1, 3)[0]+integer_log(x>>2, 3)[0]
    return n+(m:=f(n))+(n+m>=A000792(m+1))

Crossrefs

Cf. A000792, A349983.

Sequence in context: A047479 A080720 A189034 * A112250 A192067 A347653

Adjacent sequences: A392779 A392780 A392781 * A392783 A392784 A392785

Keyword

nonn,easy

Author

Chai Wah Wu, Jan 23 2026

Status

approved