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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). 9
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

Table of n, a(n) for n=1..25.

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

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 August 2 02:53 EDT 2021. Contains 346409 sequences. (Running on oeis4.)