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%I #6 Mar 20 2023 22:57:29
%S 2,12,34,217,731,1743,2183,3759,21179,121179,931303,1931303,11175573,
%T 11379829,17896361,18419721,96919009,889910891,1889910891,2742368917,
%U 25741106537,110203233579,679231622473,1679231622473,7921256096487
%N a(1) = 2, 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).
%H Sean A. Irvine, <a href="/A062094/b062094.txt">Table of n, a(n) for n = 1..250</a>
%e a(1) = 2 is a prime hence a(2) = 12; a(3) = 34, 3*4 = 12 and 3<4.
%t 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, 2, 25]
%Y Cf. A003681, A062095.
%K nonn,easy,base
%O 1,1
%A _Amarnath Murthy_, Jun 16 2001
%E More terms from _Robert G. Wilson v_, Aug 08 2001
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