A345143 Reflection of the concatenation of the previous two terms minus the previous term.

0, 1, 9, 82, 207, 70021, 11937681, 1867379174326, 623471971900739499585, 5859949370091168271294333980238096, 6908320893334921728606040790129494417723642675198936230

Offset: 0

Author

George Bull, Jun 09 2021

Keywords

• nonn
• base

Examples

			a(4) = 207 since 28(9) - 82 = 207.
		

Crossrefs

Cf. A004086, A068109.

Programs

Maple

a:= proc(n) option remember; `if`(n<2, n, (s-> parse(cat(seq(
      s[-i], i=1..length(s))))-a(n-1))(cat("", a(n-2), a(n-1))))
    end:
seq(a(n), n=0..11);  # Alois P. Heinz, Jun 11 2021

Mathematica

a[0] = 0; a[1] = 1; a[n_] := a[n] = FromDigits[Join @@ (Reverse @ IntegerDigits[#] & /@ {a[n - 1], a[n - 2]})] - a[n - 1]; Array[a, 11, 0] (* Amiram Eldar, Jun 09 2021 *)

Python

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

Formula

a(n) = A004086(a(n-2)||a(n-1)) - a(n-1) for n >= 2, a(n) = n for n <= 1.