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A014255 Expansion of (1+2*x+3*x^2)/((1-x)*(1-x^2)^2). +0
2
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)
OFFSET

0,2

COMMENT

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

FORMULA

a(n) = (n+1)^2 - floor((n+1)/2)^2. - Frank Adams-Watters (FrankTAW(AT)Netscape.net), May 26 2006

CROSSREFS

Sequence in context: A005660 A086813 A103888 this_sequence A022407 A007434 A128303

Adjacent sequences: A014252 A014253 A014254 this_sequence A014256 A014257 A014258

KEYWORD

nonn,easy

AUTHOR

njas

page 1

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Last modified July 4 18:25 EDT 2008. Contains 140886 sequences.


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