cp's OEIS Frontend

A317947 Concatenate n and n-1 in binary.

%I A317947 #13 Aug 12 2018 16:13:24
%S A317947 10,101,1110,10011,101100,110101,111110,1000111,10011000,10101001,
%T A317947 10111010,11001011,11011100,11101101,11111110,100001111,1000110000,
%U A317947 1001010001,1001110010,1010010011,1010110100,1011010101,1011110110,1100010111,1100111000,1101011001,1101111010,1110011011,1110111100
%N A317947 Concatenate n and n-1 in binary.
%H A317947 Robert Israel, <a href="/A317947/b317947.txt">Table of n, a(n) for n = 1..10000</a>
%F A317947 a(n) = A007088(n-1)+10^(1+A000523(n-1))*A007088(n) for n >= 2. - _Robert Israel_, Aug 12 2018
%p A317947 f:= proc(n) local A;
%p A317947   A:= convert(n-1,binary);
%p A317947   10^length(A)*convert(n,binary)+A
%p A317947 end proc:
%p A317947 f(1):= 10:
%p A317947 map(f, [$1..100]); # _Robert Israel_, Aug 12 2018
%o A317947 (PARI) zbinary(n) = if (n, binary(n), [0]);
%o A317947 a(n) = fromdigits(concat(zbinary(n), zbinary(n-1))); \\ _Michel Marcus_, Aug 12 2018
%Y A317947 Cf. A000523, A007088, A127423 (base 10 version).
%K A317947 nonn,base
%O A317947 1,1
%A A317947 _N. J. A. Sloane_, Aug 11 2018
%E A317947 More terms from _Robert Israel_, Aug 12 2018