|
%I #13 Jan 03 2020 04:36:17
%S 1,4,61,442,8671,48643,275491,4691011,44046781,421781671,4866217861,
%T 44417846491,469583176771,4807072338781,42155398282291,
%U 461921395126861,4447050855867481,42996432430288771,480551127927589171,4866530171154022291,46198061648602166491
%N Numbers multiplied by 4 and written backwards.
%H Alois P. Heinz, <a href="/A132064/b132064.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = reverse(4*a(n-1)) where a(1) = 1
%F Conjecture: a(n)^(1/n) tends to 10. - _Vaclav Kotesovec_, Jan 03 2020
%e 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
%p a:= proc(n) option remember; `if`(n=1, 1,
%p (s-> parse(cat(s[-i]$i=1..length(s))))(""||(4*a(n-1))))
%p end:
%p seq(a(n), n=1..30); # _Alois P. Heinz_, Apr 09 2015
%t NestList[IntegerReverse[4#]&,1,20] (* Requires Mathematica version 11 or later *) (* _Harvey P. Dale_, Dec 09 2017 *)
%Y Cf. A036447 (*2), A163632 (*3), A045539 (*5), A132078 (*6), A132114 (*7), A132113 (*8), A133361 (*9).
%K base,nonn
%O 1,2
%A Rachit Agrawal (rachit_agrawal(AT)daiict.ac.in), Oct 30 2007
%E More terms from _Alois P. Heinz_, Apr 09 2015
|
