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A063269 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). 0
3, 13, 113, 1113, 2153, 12153, 34051, 172003, 1311313, 3473779, 5365543, 16913173, 34014973, 229148537, 479347809, 1807726517, 11807726517, 20529575173, 69833293981, 179443389167, 230839777353, 376946592451 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..22.

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, 3, 24 ]

CROSSREFS

Cf. A003681, A062094 and A062095.

Sequence in context: A006860 A181083 A090537 * A105431 A062447 A053583

Adjacent sequences:  A063266 A063267 A063268 * A063270 A063271 A063272

KEYWORD

base,nonn

AUTHOR

Robert G. Wilson v, Aug 08 2001

STATUS

approved

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Last modified February 20 14:56 EST 2019. Contains 320327 sequences. (Running on oeis4.)