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1, 1, 2, 6, 17, 57, 233, 989, 4602, 23794, 129285, 751973, 4680041, 30523105, 210159654, 1521122754, 11481486845, 90604333205, 744420806913, 6348340033789, 56202980961206, 514994183598470, 4877587872447801, 47711923353493817, 481072714151555073, 4995769099914083313
(list;
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refs;
listen;
history;
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internal format)
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OFFSET
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1,3
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LINKS
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FORMULA
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a(n) = Sum_{k = 0..floor((n-1)/2)} Stirling2(n+1,n-2*k)/binomial(n-2*k+1,2).
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MAPLE
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seq(add( Stirling2(n+1, n-2*k)/binomial(n-2*k+1, 2), k = 0..floor((n-1)/2) ), n = 1..30);
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PROG
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(PARI) a(n) = sum(k = 0, (n-1)\2, stirling(n+1, n-2*k, 2)/binomial(n-2*k+1, 2)); \\ Michel Marcus, May 21 2023
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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