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A287884 a(n) = A287883(2^n).

%I A287884 #13 Feb 19 2020 08:02:16
%S A287884 1,3,28,285,2874,29207,293858,2947737,29514646,295386007,2955097334,
%T A287884 29553146265,295558787590,2955735778303,29557796658178,
%U A287884 295579887348019,2955811931652374,29558179966812569,295582026870344468,2955821271264504051,29558218775337316364,295582213433030953645
%N A287884 a(n) = A287883(2^n).
%C A287884 These are the terms where A287883 makes a dramatic jump.
%C A287884 It would be nice to have a formula.
%H A287884 Jinyuan Wang, <a href="/A287884/b287884.txt">Table of n, a(n) for n = 0..30</a>
%t A287884 co[n_,k_]:=Nest[Flatten[IntegerDigits[{#, n}]]&, n, k-1]; A037276=Table[FromDigits[Flatten[IntegerDigits[co@@@FactorInteger[n]]]], {n, 3 10^5}]; Table[Sum[A037276[[k]], {k, 1, 2^n}], {n, 0, 18}] (* _Vincenzo Librandi_, Oct 01 2017 *)
%o A287884 (PARI) A037276(k) = {for(i=1, #k=factor(k)~, k[1, i]=concat(vector(k[2, i], j, Str(k[1, i])))); eval(concat(k[1, ])); }
%o A287884 lista(nn) = {my(s=1); print1(s); for(n=0, nn, s+=sum(k=2^n+1, 2*2^n, A037276(k)); print1(", ", s)); } \\ _Jinyuan Wang_, Feb 19 2020
%Y A287884 Cf. A037276, A287883.
%K A287884 nonn,base
%O A287884 0,2
%A A287884 _N. J. A. Sloane_, Jun 20 2017
%E A287884 a(15)-a(18) from _Vincenzo Librandi_, Oct 01 2017
%E A287884 a(19)-a(21) from _Jinyuan Wang_, Feb 19 2020