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 A048985 Working in base 2, replace n with the concatenation of its prime divisors in increasing order (write answer in base 10). 10
 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)
 OFFSET 1,2 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 Patrick De Geest, Home Primes EXAMPLE 15 = 3*5 -> 11.101 -> 11101 = 29, so a(15) = 29. MATHEMATICA f[n_] := FromDigits[ Flatten[ IntegerDigits[ Flatten[ Table[ #1, {#2}] & @@@ FactorInteger@n], 2]], 2]; Array[f, 64] (* Robert G. Wilson v, Jun 02 2010 *) PROG (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 (Python) from sympy import factorint def a(n): if n == 1: return 1 return int("".join(bin(p)[2:]*e for p, e in factorint(n).items()), 2) print([a(n) for n in range(1, 65)]) # Michael S. Branicky, Oct 07 2022 CROSSREFS Cf. A037276, A048986, A064841. Cf. A193652, A029744 (record values and where they occur). Cf. A027746. Sequence in context: A216937 A351629 A230625 * A337183 A348058 A112417 Adjacent sequences: A048982 A048983 A048984 * A048986 A048987 A048988 KEYWORD nonn,easy,nice,base,look AUTHOR N. J. A. Sloane EXTENSIONS More terms from Sam Alexander (pink2001x(AT)hotmail.com) and Michel ten Voorde STATUS approved

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Last modified June 14 14:31 EDT 2024. Contains 373400 sequences. (Running on oeis4.)