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A026165
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Number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 2, |s(1) - s(0)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also sum of numbers in row n+1 of the array T in A026148.
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0
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1, 2, 6, 17, 49, 141, 407, 1177, 3411, 9904, 28808, 83931, 244895, 715534, 2093262, 6130767, 17974779, 52751358, 154950378, 455524203, 1340182539, 3945723033, 11624603235, 34268836707, 101081770181, 298320243976, 880875609552
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n) = Sum_{k=0..n} binomial(n, k)*binomial(k+1, floor(k/2)). - Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 18 2003
E.g.f.: exp(x)/x^2*((2*x^2-2*x)*BesselI(0, 2*x)+(2-x+2*x^2)*BesselI(1, 2*x)). - Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 23 2003
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CROSSREFS
| Sequence in context: A052536 A122100 A122099 * A148445 A148446 A173993
Adjacent sequences: A026162 A026163 A026164 * A026166 A026167 A026168
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KEYWORD
| nonn
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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