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A178910
Binary XOR of divisors of n.
19
1, 3, 2, 7, 4, 6, 6, 15, 11, 12, 10, 14, 12, 10, 8, 31, 16, 29, 18, 28, 16, 30, 22, 30, 29, 20, 16, 18, 28, 24, 30, 63, 40, 48, 32, 49, 36, 54, 40, 60, 40, 48, 42, 54, 44, 58, 46, 62, 55, 39, 32, 36, 52, 48, 56, 34, 40, 36, 58, 56, 60, 34, 38, 127, 72, 120, 66, 112, 80, 96, 70
OFFSET
1,2
COMMENTS
If 2^k <= n < 2^(k+1), then also 2^k <= a(n) < 2^(k+1), since any proper divisor of n is < 2^k.
LINKS
PROG
(PARI) a(n)=local(ds, r); ds=divisors(n); for(k=1, #ds, r=bitxor(r, ds[k])); r
(Haskell)
import Data.Bits (xor)
a178910 = foldl1 xor . a027750_row :: Integer -> Integer
-- Reinhard Zumkeller, Nov 17 2012
CROSSREFS
Cf. A027750, A072594; subsequences A028982 (odd), A028982 (even).
Sequence in context: A371974 A344878 A344875 * A182651 A175055 A351207
KEYWORD
base,nonn,look
AUTHOR
STATUS
approved