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A063403 a(1) = 8, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).

%I A063403 #3 Mar 30 2012 17:30:32
%S A063403 8,24,46,223,1223,11223,87129,189461,414621,2072003,12072003,34024001,
%T A063403 163920759,354640253,1074732999,7377145687,17377145687,57053304579,
%U A063403 393145173803,834736688841,8062231035367,26899299722333,27745499695017
%N A063403 a(1) = 8, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).
%t A063403 f[ n_Integer ] := (d = Divisors[ n ]; l = Length[ d ]; If[ EvenQ[ l ], ToExpression[ ToString[ d[[ l/2 ] ]] <> ToString[ d[[ l/2 + 1 ]] ]], ToExpression[ ToString[ d[[ l/2 + .5 ] ]] <> ToString[ d[[ l/2 + .5 ] ]] ]] ); NestList[ f, 8, 25 ]
%Y A063403 Cf. A003681, A062094 and A062095.
%K A063403 base,nonn
%O A063403 1,1
%A A063403 _Robert G. Wilson v_, Aug 09 2001