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A007461
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Shifts left under AND-convolution with itself.
(Formerly M0117)
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7
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1, 1, 2, 1, 2, 4, 0, 5, 2, 4, 0, 10, 0, 12, 4, 13, 6, 12, 0, 18, 12, 20, 20, 36, 20, 36, 16, 44, 32, 60, 40, 73, 50, 56, 40, 58, 44, 52, 60, 84, 36, 112, 88, 108, 136, 132, 152, 178, 136, 232, 108, 260, 244, 256, 304, 288
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listen;
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OFFSET
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0,3
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COMMENTS
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
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MAPLE
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a:= proc(n) option remember; `if`(n=0, 1, add(
Bits[And](a(i), a(n-1-i)), i=0..n-1))
end:
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MATHEMATICA
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a[0]=1; a[1]=1; a[n_] := a[n] = Sum[BitAnd[a[k], a[n-k-1]], {k, 0, n-1}]; Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Sep 07 2012 *)
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PROG
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(Haskell)
import Data.Bits ((.&.))
a007461 n = a007461_list !! n
a007461_list = 1 : f [1, 1] where
f xs = x : f (x:xs) where
x = sum $ zipWith (.&.) xs $ tail $ reverse xs :: Integer
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CROSSREFS
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KEYWORD
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nonn,nice,eigen
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AUTHOR
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STATUS
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approved
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