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A368839
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a(n) = n! * (n+1)! * (n+2)! * Sum_{k=0..n} 1/(k! * (k+1)! * (k+2)!).
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2
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1, 7, 169, 10141, 1216921, 255553411, 85865946097, 43276436832889, 31159034519680081, 30847444174483280191, 40718626310317929852121, 69873162748505567626239637, 152602987442736159695707367209, 416606155718669715969281112480571
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = n*(n+1)*(n+2)*a(n-1) + 1.
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PROG
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(PARI) a(n) = n!*(n+1)!*(n+2)!*sum(k=0, n, 1/(k!*(k+1)!*(k+2)!));
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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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