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%I #15 Oct 27 2023 22:05:37
%S 1,4,16,424,16816,42432424,1681612816816,42432424483242432424,
%T 168161281681616321281681612816816,
%U 42432424483242432424424128483242432424483242432424
%N a(1) = 1, a(n)= number obtained by replacing each digit of a(n-1) with four times its value.
%H Michael De Vlieger, <a href="/A061580/b061580.txt">Table of n, a(n) for n = 1..16</a>
%t NestList[FromDigits@ Flatten@ Map[IntegerDigits, 4*IntegerDigits[#]] &, 1, 9] (* _Michael De Vlieger_, Feb 25 2023 *)
%Y Cf. A061581, A061582, A061583, A061584, A061585, A061586, A061587.
%K nonn,base,easy
%O 1,2
%A _Amarnath Murthy_, May 13 2001
%E More terms from Larry Reeves (larryr(AT)acm.org) and _Asher Auel_, May 15 2001
%E a(9) corrected by _N. J. A. Sloane_, Jan 23 2017 at the suggestion of Carolyn Liao.
%E a(10) corrected by _Sean A. Irvine_, Feb 25 2023
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