OFFSET
0,5
COMMENTS
LINKS
EXAMPLE
The first terms, in decimal and in binary, are:
n a(n) bin(n) bin(a(n))
-- ---- ------ ---------
0 0 0 0
1 1 1 1
2 1 10 1
3 1 11 1
4 2 100 10
5 3 101 11
6 2 110 10
7 3 111 11
8 2 1000 10
9 2 1001 10
10 3 1010 11
11 3 1011 11
12 2 1100 10
13 2 1101 10
14 3 1110 11
15 3 1111 11
MATHEMATICA
A371442[n_] := FromDigits[IntegerDigits[n, 2][[1;; -1;; 2]], 2];
Array[A371442, 100, 0] (* Paolo Xausa, Mar 28 2024 *)
PROG
(PARI) a(n) = { my (b = binary(n)); fromdigits(vector(ceil(#b/2), k, b[2*k-1]), 2); }
(Python) def a(n): return int(bin(n)[::2], 2)
CROSSREFS
See A371459 for the sequence related to even-indexed bits.
KEYWORD
nonn,base,easy
AUTHOR
Rémy Sigrist, Mar 24 2024
STATUS
approved