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Search: id:A133224
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| A133224 |
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Let P(A) denote the power set of an n-element set A. Then a(n) = the sum of the sizes of the union of x and y for every x, y in P(A). |
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+0
1
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| 0, 2, 14, 78, 400, 1960, 9312, 43232, 197120, 885888, 3934720, 17307136, 75509760, 327182336, 1409343488, 6039920640, 25770065920, 109522223104, 463857647616, 1958507577344, 8246342451200
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OFFSET
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0,2
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FORMULA
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a(n) = n(2^(n-2) + 3*2^(2n-3)).
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EXAMPLE
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a(2) = 14 because for P(A) = {{},{1},{2},{1,2}} |{} union {1}| = 1, |{} union {2}| = 1, |{} union {1,2}| = 2, |{1} union {2}| = 2, |{1} union {1,2}| = 2, and |{2} union {1,2}| = 2, |{} union {}| = 0, |{1} union {1}| = 1, |{2} union {2}| = 1, |{1,2} union {1,2}| = 2, which sums to 14.
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CROSSREFS
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Cf. A027471, A002697, A082134.
Sequence in context: A119913 A104871 A034573 this_sequence A121200 A112408 A026291
Adjacent sequences: A133221 A133222 A133223 this_sequence A133225 A133226 A133227
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KEYWORD
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nonn
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AUTHOR
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Ross La Haye (rlahaye(AT)new.rr.com), Dec 30 2007, Jan 03 2008
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