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A014288
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[ Sum k!/2, k=0..n ], or floor( A003422(n+1)/2 ).
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7
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0, 1, 2, 5, 17, 77, 437, 2957, 23117, 204557, 2018957, 21977357, 261478157, 3374988557, 46964134157, 700801318157, 11162196262157, 189005910310157, 3390192763174157, 64212742967590157, 1280663747055910157
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| The first term a(0) would be a fraction if the floor( ... ) function would be omitted ; for n>=2, all terms from A003422 are even. - M. F. Hasler, Dec 16 2007
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FORMULA
| a(1)=1, a(2)=2, a(n)=(n+1)*a(n-1)-n*a(n-2). - Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 07 2002
a(0) = 0, a(n) = (1/2)*Floor[1+1*Floor[1+2*Floor[1+....+(n-1)*Floor[1+n*Floor[1]]]....]. [From Joseph E. Cooper III (easonrevant(AT)gmail.com), Aug 19 2008]
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MATHEMATICA
| Contribution from Joseph E. Cooper III (easonrevant(AT)gmail.com), Aug 19 2008: (Start)
f[x_] := {Floor[1 + (n - x[[2]])*x[[1]]], x[[2]] + 1}
Nest[f, {1, 0}, n][[1]]/2 (End)
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PROG
| (PARI) A014288(n)=sum(k=0, n, k!)>>1 \\ - M. F. Hasler, Dec 16 2007
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CROSSREFS
| Cf. A003422, A067078, A007489.
Sequence in context: A118100 A129591 A099825 * A199164 A184509 A020096
Adjacent sequences: A014285 A014286 A014287 * A014289 A014290 A014291
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Edited by M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Dec 16 2007
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