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

Author

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

Keywords

• base
• nonn

Examples

			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
		

Links

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

Crossrefs

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

Programs

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 *)

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

Extensions

More terms from Alois P. Heinz, Apr 09 2015