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%I #8 Feb 21 2016 19:51:20
%S 1,10,4,12,6,3,2,11,5,18,7,13,9,19,8,17,115,3789
%N Smallest number m such that A266998(m) = n.
%C The next term is too large to include.
%H Michel Marcus, <a href="/A266999/b266999.txt">Table of n, a(n) for n = 0..17</a>
%F A266998(a(n)) = n and A266998(m) != n for m < a(n).
%t a266999={};
%t f[n_]:=Total[IntegerDigits[n]*(IntegerDigits[n]+1)/2];
%t g[n_]:=NestWhileList[f[#]&,n,#>1&];
%t h[n_]:=Length[g[n]]-1;
%t a266998=h/@Range[10^6];
%t Do[AppendTo[a266999,First[Position[a266998,m]]],{m,0,Max[a266998]}];
%t a266999//Flatten
%o (PARI) strd(n) = {my(d = digits(n)); sum(k=1, #d, d[k]*(d[k]+1)/2);}
%o nbi(n) = {my(nb=0); while(n != 1, n = strd(n); nb++;); nb;}
%o a(n) = {my(m = 1); while(nbi(m) != n, m++); m;} \\ _Michel Marcus_, Jan 12 2016
%Y Cf. A266998.
%K base,more,nonn
%O 0,2
%A _Ivan N. Ianakiev_, Jan 10 2016
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