A215090 a(n) = Sum_{i=0..m} d(i)*3^i, where Sum_{i=0..m} d(i)*4^i is the base-4 representation of n.

0, 1, 2, 3, 3, 4, 5, 6, 6, 7, 8, 9, 9, 10, 11, 12, 9, 10, 11, 12, 12, 13, 14, 15, 15, 16, 17, 18, 18, 19, 20, 21, 18, 19, 20, 21, 21, 22, 23, 24, 24, 25, 26, 27, 27, 28, 29, 30, 27, 28, 29, 30, 30, 31, 32, 33, 33, 34, 35, 36, 36, 37, 38, 39, 27, 28, 29, 30, 30, 31, 32

Offset

0,3

Links

Seiichi Manyama, Table of n, a(n) for n = 0..10000 (terms 0..1000 from Clark Kimberling)

Formula

a(n) = 3*a(n/4) if n == 0 (mod 4); otherwise a(n) = a(n-1)+1.

Mathematica

t = Table[FromDigits[RealDigits[n, 4], 3], {n, 0, 100}]

Prog

(PARI) a(n) = fromdigits(digits(n, 4), 3); \\ Michel Marcus, May 02 2018
(Julia)
function a(n)
    m, r, b = n, 0, 1
    while m > 0
        m, q = divrem(m, 4)
        r += b * q
        b *= 3
    end
r end; [a(n) for n in 0:70] |> println # Peter Luschny, Jan 03 2021

Crossrefs

Cf. A023717.

Sequence in context: A248231 A120503 A215781 * A083544 A367328 A057353

Adjacent sequences: A215087 A215088 A215089 * A215091 A215092 A215093

Keyword

nonn,base,easy

Author

Clark Kimberling, Aug 03 2012

Status

approved