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%I #11 Dec 17 2021 00:58:37
%S 7,17,1711,211711,21172112,122112172112,122112171112212211,
%T 2122112231171112212211,21221122311721132221221112,
%U 12312211321321121721132221221112
%N Describe previous term from the right (method A - initial term is 7).
%C Method A = 'frequency' followed by 'digit'-indication.
%H Michael De Vlieger, <a href="/A022511/b022511.txt">Table of n, a(n) for n = 0..21</a>
%e The term after 1711 is obtained by saying "two 1's, one 7, one 1", which gives 211711.
%t NestList[FromDigits@ Flatten@ Map[Reverse@ Flatten@ Tally[#] &, Split@ Reverse@ IntegerDigits[#]] &, 7, 9] (* _Michael De Vlieger_, Dec 16 2021 *)
%Y Cf. A022506, A006711, A022482, A022507-A022513.
%K nonn,base,easy,nice
%O 0,1
%A _N. J. A. Sloane_
%E More terms from _Erich Friedman_
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