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A063383
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a(1) = 6, 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).
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0
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6, 23, 123, 341, 1131, 2939, 12939, 57227, 89643, 329881, 1073083, 1197553, 7171079, 17171079, 57301247, 208327509, 1171780577, 1219684137, 1478297171, 2587571433, 2795835979, 8663322733, 13666409441, 113666409441
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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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, 6, 25 ]
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CROSSREFS
| Cf. A003681, A062094 and A062095.
Sequence in context: A120775 A013258 A013264 * A013263 A013259 A012468
Adjacent sequences: A063380 A063381 A063382 * A063384 A063385 A063386
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KEYWORD
| base,nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 08 2001
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