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Search: id:A063269
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| A063269 |
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a(1) = 3, 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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1
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| 3, 13, 113, 1113, 2153, 12153, 34051, 172003, 1311313, 3473779, 5365543, 16913173, 34014973, 229148537, 479347809, 1807726517, 11807726517, 20529575173, 69833293981, 179443389167, 230839777353, 376946592451
(list; graph; listen)
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OFFSET
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1,1
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MATHEMATICA
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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, 3, 24 ]
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CROSSREFS
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Cf. A003681, A062094 and A062095.
Sequence in context: A061377 A006860 A090537 this_sequence A098406 A105431 A062447
Adjacent sequences: A063266 A063267 A063268 this_sequence A063270 A063271 A063272
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KEYWORD
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base,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 08 2001
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