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A199770
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Self-convolution with "addition" played by bitwise XOR.
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4
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1, 0, 2, 6, 18, 50, 146, 426, 1282, 3810, 11394, 34082, 102338, 306658, 919874, 2759154, 8276898, 24828386, 74484386, 223444258, 670326242, 2010964770, 6032902242, 18098635298, 54295809826, 162887261410, 488661978274, 1465985458850, 4397955924386
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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LINKS
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FORMULA
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a(1)=1, a(n) = sum ( a(i) XOR a(n-i), i = 1 .. n-1).
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MAPLE
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a:= proc(n) option remember; `if`(n=0, 1, add(
Bits[Xor](a(i), a(n-1-i)), i=0..n-1))
end:
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MATHEMATICA
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a[1] = 1; a[n_] := a[n] = Sum[BitXor[a[i], a[n - i]], {i, 1, n - 1}]; Table[a[n], {n, 30}]
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PROG
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(Haskell)
import Data.Bits (xor)
a199770 n = a199770_list !! (n-1)
a199770_list = 1 : f [1] where
f xs = y : f (y : xs) where
y = sum $ zipWith xor xs $ reverse xs :: Integer
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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