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 A062094 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). 10
 2, 12, 34, 217, 731, 1743, 2183, 3759, 21179, 121179, 931303, 1931303, 11175573, 11379829, 17896361, 18419721, 96919009, 889910891, 1889910891, 2742368917, 25741106537, 110203233579, 679231622473, 1679231622473, 7921256096487 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Sean A. Irvine, Table of n, a(n) for n = 1..250 EXAMPLE a(1) = 2 is a prime hence a(2) = 12; a(3) = 34, 3*4 = 12 and 3<4. MATHEMATICA 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] CROSSREFS Cf. A003681, A062095. Sequence in context: A055707 A055699 A244378 * A334838 A200543 A246426 Adjacent sequences: A062091 A062092 A062093 * A062095 A062096 A062097 KEYWORD nonn,easy,base,changed AUTHOR Amarnath Murthy, Jun 16 2001 EXTENSIONS More terms from Robert G. Wilson v, Aug 08 2001 STATUS approved

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Last modified March 29 18:41 EDT 2023. Contains 361599 sequences. (Running on oeis4.)