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%I #14 Sep 22 2021 07:36:59
%S 1,2,6,4,10,8,79,199,9,108,11,29,17,15,40,80,20,59,306,22,169,38,27,
%T 82,287,41,49,209,47,135,31,36,127,112,123,162,46,89,63,54,581,43,56,
%U 770,67,48,134,52,142,69,58,101,382,466,75,64,273,95,117,126,72
%N Smallest number m such that A263856(m) = n.
%C a(6949) > 22700000 if it exists. - _Chai Wah Wu_, Feb 01 2016
%H Reinhard Zumkeller and Chai Wah Wu, <a href="/A264647/b264647.txt">Table of n, a(n) for n = 1..6948</a> n = 1..391 from Reinhard Zumkeller
%F A263856(a(n)) = n and A263856(m) != n for m < a(n).
%t f[p_] := f[p] = StringJoin @@ ToString /@ Reverse[IntegerDigits[p, 2]];
%t S[n_] := S[n] = SortBy[Prime[Range[n]], f];
%t A263856[n_] := A263856[n] = FirstPosition[S[n], Prime[n]][[1]];
%t a[n_] := a[n] = For[m = 1, True, m++, If[A263856[m] == n, Return[m]]];
%t Table[Print[n, " ", a[n]]; a[n], {n, 1, 391}] (* _Jean-François Alcover_, Sep 22 2021 *)
%o (Haskell)
%o import Data.List (elemIndex); import Data.Maybe (fromJust)
%o a264647 = (+ 1) . fromJust . (`elemIndex` a263856_list)
%Y Cf. A263856.
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Nov 19 2015
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