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Search: id:A063384
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| A063384 |
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a(1) = 7, 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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| 7, 17, 117, 913, 1183, 1391, 13107, 51257, 151257, 381397, 577661, 4911789, 29116879, 112646989, 536920981, 1928258999, 11928258999, 25227472837, 46275452231, 212892173679, 370964057893, 1859199550327, 5593332415439
(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, 7, 25 ]
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CROSSREFS
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Cf. A003681, A062094 and A062095.
Sequence in context: A092340 A068172 A067185 this_sequence A165246 A118108 A147643
Adjacent sequences: A063381 A063382 A063383 this_sequence A063385 A063386 A063387
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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 09 2001
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