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A372074 a(1) = 1; thereafter a(n+1) is obtained by appending the digit-sum of a(n) to a(n).

%I A372074 #22 Jun 16 2024 16:45:46
%S A372074 1,11,112,1124,11248,1124816,112481623,11248162328,1124816232838,
%T A372074 112481623283849,11248162328384962,1124816232838496270,
%U A372074 112481623283849627077,11248162328384962707791,11248162328384962707791101,11248162328384962707791101103,11248162328384962707791101103107,11248162328384962707791101103107115
%N A372074 a(1) = 1; thereafter a(n+1) is obtained by appending the digit-sum of a(n) to a(n).
%H A372074 Paolo Xausa, <a href="/A372074/b372074.txt">Table of n, a(n) for n = 1..270</a>
%p A372074 s:=1; j1:=[s];
%p A372074 f:=proc(n) local t1,t2;
%p A372074 t1:=digsum(n);
%p A372074 t2:=length(t1); n*10^t2 + t1; end;
%p A372074 for n from 1 to 24 do s:=f(s); j1:=[op(j1),s]; od:
%p A372074 j1;
%t A372074 NestList[With[{s = DigitSum[#]}, #*10^IntegerLength[s] + s] &, 1, 20] (* _Paolo Xausa_, Jun 16 2024 *)
%o A372074 (Python)
%o A372074 from itertools import islice
%o A372074 def A372074_gen(): # generator of terms
%o A372074     yield (a:=1)
%o A372074     while True: yield (a:=(s:=sum(map(int,str(a))))+a*10**len(str(s)))
%o A372074 A372074_list = list(islice(A372074_gen(),20)) # _Chai Wah Wu_, Jun 16 2024
%Y A372074 Cf. A372075.
%Y A372074 Inspired by A359143.
%K A372074 nonn,base
%O A372074 1,2
%A A372074 _N. J. A. Sloane_, Jun 16 2024