A132064 Numbers multiplied by 4 and written backwards.

1, 4, 61, 442, 8671, 48643, 275491, 4691011, 44046781, 421781671, 4866217861, 44417846491, 469583176771, 4807072338781, 42155398282291, 461921395126861, 4447050855867481, 42996432430288771, 480551127927589171, 4866530171154022291, 46198061648602166491

Offset

1,2

Links

Alois P. Heinz, Table of n, a(n) for n = 1..1000

Formula

a(n) = reverse(4*a(n-1)) where a(1) = 1

Conjecture: a(n)^(1/n) tends to 10. - Vaclav Kotesovec, Jan 03 2020

Example

a(4) = reverse(4*a(3)) = reverse(4*reverse(4*a(2))) = reverse(4*reverse(4*reverse(4*a(1)))) = reverse(4*reverse(4*4)) = reverse(4*61) = reverse(244) = 442

Maple

a:= proc(n) option remember; `if`(n=1, 1,
      (s-> parse(cat(s[-i]$i=1..length(s))))(""||(4*a(n-1))))
    end:
seq(a(n), n=1..30);  # Alois P. Heinz, Apr 09 2015

Mathematica

NestList[IntegerReverse[4#]&, 1, 20] (* Requires Mathematica version 11 or later *) (* Harvey P. Dale, Dec 09 2017 *)

Crossrefs

Cf. A036447 (*2), A163632 (*3), A045539 (*5), A132078 (*6), A132114 (*7), A132113 (*8), A133361 (*9).

Sequence in context: A129452 A131014 A118005 * A378553 A229666 A252973

Adjacent sequences: A132061 A132062 A132063 * A132065 A132066 A132067

Keyword

base,nonn

Author

Rachit Agrawal (rachit_agrawal(AT)daiict.ac.in), Oct 30 2007

Extensions

More terms from Alois P. Heinz, Apr 09 2015

Status

approved