A068109 a(1) = 0, a(2) = 1, a(n) = concatenate(a(n-1) and a(n-2)) - a(n-1).

0, 1, 9, 82, 747, 74035, 73961712, 7396097312323, 739609723836276649389, 7396097238362026884173559820662934, 7396097238362026884166163723424572712725550276455986455

Offset: 1

Author

Benoit Cloitre, Mar 21 2002

Keywords

• nonn
• base
• easy

Examples

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

Links

• Stefano Spezia, Table of n, a(n) for n = 1..17

Programs

Maple

a:= proc(n) option remember; `if`(n<3, n-1, (l->
      add(l[i]*10^(i-1), i=1..nops(l))-a(n-1))(map(
      x-> convert(x, base, 10)[], [a(n-2),a(n-1)])))
    end:
seq(a(n), n=1..12);  # Alois P. Heinz, Jun 09 2021

Mathematica

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 *)

Python

def f(v): return int((str(v[-1])+str(v[-2]))) - v[-1]
def aupton(nn):
    alst = [0, 1]
    for n in range(2, nn+1): alst.append(f(alst))
    return alst[:nn+1]
print(aupton(10)) # Michael S. Branicky, Jun 09 2021