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 A089887 Number of subsets of {1,.., n} containing no squares. 4
 1, 2, 4, 4, 8, 16, 32, 64, 64, 128, 256, 512, 1024, 2048, 4096, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = Product(2-A010052(k): 1<=k<=n) = A089886(n,0) = A000079(n)-A089888(n). LINKS FORMULA a(n) = 2^(n-n^(1/2)). PROG (PARI) a(n)=2^(n-sqrtint(n)) \\ Charles R Greathouse IV, Apr 09 2012 CROSSREFS Cf. A089889, A089890. Sequence in context: A181217 A223569 A227594 * A161816 A240347 A160124 Adjacent sequences:  A089884 A089885 A089886 * A089888 A089889 A089890 KEYWORD nonn AUTHOR Reinhard Zumkeller, Nov 13 2003 STATUS approved

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