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A247873 For bases b = 2, 3, ..., n, let the base-b expansion of n be [c_{1,b} c_{2,b} .. c_{r_b,b}], with the most significant "digit" on the left, 0 <= c_{i,b} < b, and c_{1,b} != 0; then a(n) is the number whose base-n expansion is c_{1,n} c_{2,n} ... c_{r_n,n} c_{1,n-1} ... c_{1,2} c_{2,2} ... c_{r_2,2}.

%I A247873 #39 Oct 02 2014 14:00:58
%S A247873 2,31,4432,410276,62490570,14171701216,35813773615616,
%T A247873 152181888842647477,101112131420221011010,82143288287525988974045,
%U A247873 80099420009719637413225296,92321614375701368079704516014,124155371020622584901673311361738,192664414286229496774895472345022366
%N A247873 For bases b = 2, 3, ..., n, let the base-b expansion of n be [c_{1,b} c_{2,b} .. c_{r_b,b}], with the most significant "digit" on the left, 0 <= c_{i,b} < b, and c_{1,b} != 0; then a(n) is the number whose base-n expansion is c_{1,n} c_{2,n} ... c_{r_n,n} c_{1,n-1} ... c_{1,2} c_{2,2} ... c_{r_2,2}.
%C A247873 The base-n expansion of a(n) is the concatenations of the expansions of n in bases n, n-1, ..., 3, 2, regarding all the coefficients as numbers in the range 0 to n-1.
%H A247873 Hiroaki Yamanouchi, <a href="/A247873/b247873.txt">Table of n, a(n) for n = 2..100</a>
%e A247873 For n = 4 we first find 4 in base 4 = 1,0, then 4 in base 3 = 1,1, and 4 in base 2 = 1,0,0. The full string we now have is '1,0,1,1,1,0,0'. This is the base-4 expansion of the number a(4) = 1*4^6 + 0*4^5 + 1*4^4 + 1*4^3 + 1*4^2 + 0*4^1 + 0*4^0 = 4432.
%Y A247873 Cf. A247878, A247880.
%K A247873 nonn,base,easy
%O A247873 2,1
%A A247873 _Talha Ali_, Sep 25 2014
%E A247873 Definition revised by _N. J. A. Sloane_, Sep 27 2014
%E A247873 a(7)-a(15) from _Hiroaki Yamanouchi_, Oct 02 2014