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 A218388 Bitwise OR of all divisors of n. 5
 1, 3, 3, 7, 5, 7, 7, 15, 11, 15, 11, 15, 13, 15, 15, 31, 17, 31, 19, 31, 23, 31, 23, 31, 29, 31, 27, 31, 29, 31, 31, 63, 43, 51, 39, 63, 37, 55, 47, 63, 41, 63, 43, 63, 47, 63, 47, 63, 55, 63, 51, 63, 53, 63, 63, 63, 59, 63, 59, 63, 61, 63, 63, 127, 77, 127 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) <= A003817(n); a(A000040(n)) = A000040(n). LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..8191 Eric Weisstein's World of Mathematics, OR Wikipedia, Bitwise operation OR Index entries for sequences related to binary expansion of n EXAMPLE n=20: divisors(20) = {1, 2, 4, 5, 10, 20}, 00001 OR 00010 OR 00100 OR 00101 OR 01010 OR 10100 = 11111 -> a(20) = 31; n=21: divisors(21) = {1, 3, 7, 21}, 00001 OR 00011 OR 00111 OR 10101 = 10111 -> a(21) = 23; n=22: divisors(22) = {1, 2, 11, 22}, 00001 OR 00010 OR 01011 OR 10110 = 11111 -> a(22) = 31; n=23: divisors(23) = {1, 23}, 00001 OR 10111 = 10111 -> a(23) = 23; n=24: divisors(24) = {1, 2, 3, 4, 6, 8, 12, 24}, 00001 OR 00010 OR 00011 OR 00100 OR 00110 OR 01000 OR 01100 OR 11000 = 11111 -> a(24) = 31; n=25: divisors(25) = {1, 5, 25}, 00001 OR 00101 OR 11001 = 11101 -> a(25) = 29. MATHEMATICA Table[BitOr@@Divisors[n], {n, 70}] (* Harvey P. Dale, Feb 27 2013 *) PROG (Haskell) import Data.Bits ((.|.)) a218388 = foldl1 (.|.) . a027750_row :: Integer -> Integer CROSSREFS Cf. A027750, A000225 (subsequence), A123345, A218403. Sequence in context: A318456 A209085 A086799 * A308340 A161427 A365212 Adjacent sequences: A218385 A218386 A218387 * A218389 A218390 A218391 KEYWORD nonn,base,look AUTHOR Reinhard Zumkeller, Oct 27 2012 STATUS approved

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Last modified May 27 01:42 EDT 2024. Contains 372847 sequences. (Running on oeis4.)