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Write n in Elias's delta code, interchange the 1's and 0's and convert it back to decimal.
2

%I #6 Jan 20 2017 23:45:46

%S 0,7,6,11,10,9,8,63,62,61,60,59,58,57,56,111,110,109,108,107,106,105,

%T 104,103,102,101,100,99,98,97,96,191,190,189,188,187,186,185,184,183,

%U 182,181,180,179,178,177,176,175,174,173,172,171,170,169,168,167,166,165,164,163,162

%N Write n in Elias's delta code, interchange the 1's and 0's and convert it back to decimal.

%H Indranil Ghosh, <a href="/A281313/b281313.txt">Table of n, a(n) for n = 1..10000</a>

%e For n = 10, the Elias delta code for 10 is '11000010' and after interchanging the 0's and 1's it becomes '00111101'. Now, 111101_2 = 61_10. So, a(10) = 61.

%o (Python)

%o def a(n):

%o ....s=""

%o ....for i in A281150(n):

%o ........if i=="1":

%o ............s+="0"

%o ........else:

%o ............s+="1"

%o ....return int(s,2)

%Y Cf. A035327, A054429 (n is converted to Elias gamma code, the 1's and 0's are interchanged and the code is converted back to decimal, for n>1), A281150.

%K nonn,base

%O 1,2

%A _Indranil Ghosh_, Jan 19 2017