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Search: id:A014255
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| A014255 |
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Expansion of (1+2*x+3*x^2)/((1-x)*(1-x^2)^2). |
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+0
2
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| 1, 3, 8, 12, 21, 27, 40, 48, 65, 75, 96, 108, 133, 147, 176, 192, 225, 243, 280, 300, 341, 363, 408, 432, 481, 507, 560, 588, 645, 675, 736, 768, 833, 867, 936, 972, 1045, 1083, 1160, 1200, 1281, 1323, 1408, 1452, 1541, 1587, 1680, 1728, 1825, 1875, 1976, 2028
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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A002620(n+1) is the n-th partial arithmetic mean. - Michael Somos Feb 14 2004
The smallest integer greater than a(n-1) such that the n-th partial arithmetic mean is an integer is a(n) if n is odd or a(n)-(n+1) if n is even. - Michael Somos Feb 14 2004
Beginning with 1, the smallest integer greater than the previous term such that no three consecutive terms are in arithmetic progression and the n-th partial arithmetic mean is an integer. - Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 05 2004
The maximum possible number of black cells in a solution to an (n+1) X (n+1) nurikabe grid. [From Tanya Khovanova (tanyakh(AT)yahoo.com), Feb 24 2009]
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FORMULA
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a(n) = (n+1)^2 - floor((n+1)/2)^2. - Frank Adams-Watters (FrankTAW(AT)Netscape.net), May 26 2006
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CROSSREFS
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Sequence in context: A005660 A086813 A103888 this_sequence A022407 A158022 A007434
Adjacent sequences: A014252 A014253 A014254 this_sequence A014256 A014257 A014258
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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