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Search: id:A026010
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| A026010 |
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a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| = 1 for i = 1,2,...,n and s(0) = 2. Also a(n) = sum of numbers in row n+1 of array T defined in A026009. |
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+0
4
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| 1, 2, 4, 7, 14, 25, 50, 91, 182, 336, 672, 1254, 2508, 4719, 9438, 17875, 35750, 68068, 136136, 260338, 520676, 999362, 1998724, 3848222, 7696444, 14858000, 29716000, 57500460, 115000920, 222981435, 445962870, 866262915, 1732525830, 3370764540
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(2n) = (3n + 1)/(2n + 1) C(2n + 1, n), n>=0 a(2n-1) = a(2n)/2, n>=1 - Herbert Kociemba (kociemba(AT)t-online.de), May 08 2004
a(n)=sum{k=0..n, binomial(floor((n+k)/2), floor(k/2))} - Paul Barry (pbarry(AT)wit.ie), Jul 15 2004
Inverse binomial transform of A005774: (1, 3, 9, 26, 75, 216,...). - Gary W. Adamson (qntmpkt(AT)yahoo.com), Oct 22 2007
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CROSSREFS
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First differences of A050168. Pairwise sums of A037952.
Cf. A005774.
Sequence in context: A072810 A167606 A065455 this_sequence A088813 A097596 A054191
Adjacent sequences: A026007 A026008 A026009 this_sequence A026011 A026012 A026013
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KEYWORD
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nonn
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AUTHOR
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Clark Kimberling (ck6(AT)evansville.edu)
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