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A048985
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Working in base 2, replace n with the concatenation of its prime divisors in increasing order (write answer in base 10).
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10
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1, 2, 3, 10, 5, 11, 7, 42, 15, 21, 11, 43, 13, 23, 29, 170, 17, 47, 19, 85, 31, 43, 23, 171, 45, 45, 63, 87, 29, 93, 31, 682, 59, 81, 47, 175, 37, 83, 61, 341, 41, 95, 43, 171, 125, 87, 47, 683, 63, 173, 113, 173, 53, 191, 91, 343, 115, 93, 59, 349, 61, 95, 127, 2730
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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LINKS
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Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
P. De Geest, Home Primes
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EXAMPLE
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15 = 3*5 -> 11.101 -> 11101 = 29, so a(15) = 29.
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MATHEMATICA
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f[n_] := FromDigits[ Flatten[ IntegerDigits[ Flatten[ Table[ #1, {#2}] & @@@ FactorInteger@n], 2]], 2]; Array[f, 64] (* Robert G. Wilson v, Jun 02 2010 *)
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PROG
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(Haskell)
-- import Data.List (unfoldr)
a048985 = foldr (\d v -> 2 * v + d) 0 . concatMap
(unfoldr (\x -> if x == 0 then Nothing else Just $ swap $ divMod x 2))
. reverse . a027746_row
-- Reinhard Zumkeller, Jul 16 2012
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CROSSREFS
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Cf. A037276, A048986, A064841.
Cf. A193652, A029744 (record values and where they occur).
Cf. A027746.
Sequence in context: A213962 A216937 A230625 * A337183 A112417 A139693
Adjacent sequences: A048982 A048983 A048984 * A048986 A048987 A048988
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KEYWORD
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nonn,easy,nice,base,look
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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More terms from Sam Alexander (pink2001x(AT)hotmail.com) and Michel ten Voorde
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STATUS
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approved
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