A068109 - OEIS

%I #20 Apr 28 2023 11:22:19

%S 0,1,9,82,747,74035,73961712,7396097312323,739609723836276649389,

%T 7396097238362026884173559820662934,

%U 7396097238362026884166163723424572712725550276455986455

%N a(1) = 0, a(2) = 1, a(n) = concatenate(a(n-1) and a(n-2)) - a(n-1).

%H Stefano Spezia, <a href="/A068109/b068109.txt">Table of n, a(n) for n = 1..17</a>

%e a(5) = 82|9 - 82 = 747.

%p a:= proc(n) option remember; `if`(n<3, n-1, (l->

%p       add(l[i]*10^(i-1), i=1..nops(l))-a(n-1))(map(

%p       x-> convert(x, base, 10)[], [a(n-2),a(n-1)])))

%p     end:

%p seq(a(n), n=1..12);  # _Alois P. Heinz_, Jun 09 2021

%t a[1]=0; a[2]=1; a[n_]:=FromDigits[Join[IntegerDigits[a[n-1]],IntegerDigits[a[n-2]]]]-a[n-1]; Array[a,12] (* _Stefano Spezia_, Apr 25 2023 *)

%o (Python)

%o def f(v): return int((str(v[-1])+str(v[-2]))) - v[-1]

%o def aupton(nn):

%o     alst = [0, 1]

%o     for n in range(2, nn+1): alst.append(f(alst))

%o     return alst[:nn+1]

%o print(aupton(10)) # _Michael S. Branicky_, Jun 09 2021

%K nonn,base,easy

%O 1,3

%A _Benoit Cloitre_, Mar 21 2002