A090078 In binary expansion of n, reduce contiguous blocks of 0's to 0.

0, 1, 2, 3, 2, 5, 6, 7, 2, 5, 10, 11, 6, 13, 14, 15, 2, 5, 10, 11, 10, 21, 22, 23, 6, 13, 26, 27, 14, 29, 30, 31, 2, 5, 10, 11, 10, 21, 22, 23, 10, 21, 42, 43, 22, 45, 46, 47, 6, 13, 26, 27, 26, 53, 54, 55, 14, 29, 58, 59, 30, 61, 62, 63, 2, 5, 10, 11, 10, 21, 22, 23, 10, 21

Offset

0,3

Links

Table of n, a(n) for n=0..73.

Index entries for sequences related to binary expansion of n

Formula

a(a(n)) = a(n).

a(A090077(n)) = A090077(a(n)) = A090079(n).

Example

100 -> '1100100' -> 11[00]1[00] -> 11[0]1[0] -> '11010' -> 26=a(100).

Prog

(PARI) a(n)=my(v=binary(n), t); for(i=1, #v, if(v[i], t+=t+1, t%2, t+=t)); t \\ Charles R Greathouse IV, Aug 17 2016
(Python)
def a(n):
    b = bin(n)[2:]
    while "00" in b: b = b.replace("00", "0")
    return int(b, 2)
print([a(n) for n in range(81)]) # Michael S. Branicky, Jul 27 2022

Crossrefs

Cf. A007088, A090079, A090077.

Sequence in context: A072775 A304768 A243057 * A325814 A325126 A327937

Adjacent sequences: A090075 A090076 A090077 * A090079 A090080 A090081

Keyword

nonn,base,easy

Author

Reinhard Zumkeller, Nov 20 2003

Status

approved