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Search: id:A057552
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| A057552 |
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Sum_{k=0..n} C(2k+2,k). |
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+0
2
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| 1, 5, 20, 76, 286, 1078, 4081, 15521, 59279, 227239, 873885, 3370029, 13027729, 50469889, 195892564, 761615284, 2965576714, 11563073314, 45141073924, 176423482324, 690215089744, 2702831489824, 10593202603774, 41550902139550
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f.: 1/2*(2*x+(1-4*x)^(1/2)-1)/(1-4*x)^(1/2)/x^2/(-1+x). - Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 10 2003
sum(igcd(binomial(2*j,j+1)),j=0..n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 25 2006
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MAPLE
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a:=n->sum(igcd(binomial(2*j, j+1)), j=0..n): seq(a(n), n=1..24); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 25 2006
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CROSSREFS
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Cf. A000108.
Sequence in context: A061278 A000758 A005283 this_sequence A129869 A079737 A028814
Adjacent sequences: A057549 A057550 A057551 this_sequence A057553 A057554 A057555
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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), Sep 07 2000
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