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A063424 a(1) = 10, 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
10, 25, 55, 511, 773, 1773, 9197, 17541, 91949, 143643, 347881, 3311051, 13311051, 35433757, 71499067, 72619847, 74179791, 82678973, 613313481, 1551395431, 1679289793, 4339053251, 6529966449, 9370214693, 71338602099, 222407320757 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..26.

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, 10, 25 ]

CROSSREFS

Cf. A003681, A062094 and A062095.

Sequence in context: A072277 A283243 A263310 * A137930 A251310 A251194

Adjacent sequences: A063421 A063422 A063423 * A063425 A063426 A063427

KEYWORD

base,nonn

AUTHOR

Robert G. Wilson v, Aug 09 2001

STATUS

approved

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Last modified January 27 19:27 EST 2023. Contains 359846 sequences. (Running on oeis4.)