Search: id:A059480
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%I A059480
%S A059480 1,1,4,8,28,76,272,880,3328,12128,48736,194272,827840,3547648,15965248,
%T A059480 72727616,344136832,1653233920,8191833728,41256512128,213285020416,
%U A059480 1120928287232,6026483756800,32928762650368,183590856570368
%N A059480 A recurrence equation.
%H A059480 Harry J. Smith, <a href="b059480.txt">Table of n, a(n) for n=0,...,200</
               a>
%H A059480 S. Kitaev and T. Mansour, <a href="http://arXiv.org/abs/math.CO/0209340">
               On multi-avoidance of generalized patterns</a>.
%F A059480 a(n) = a(n - 1) + (n + 1)*a(n - 2); a(0) = a(1) = 1; E.g.f. = ( - 2*(1 
               + x) + e^((x*(2 + x))/2)*(2 + x*(2 + x))*(2 + Sqrt[2*e*Pi]*erf[1/
               Sqrt[2]]) - e^((1 + x)^2/2)*Sqrt[2*Pi]*(2 + x*(2 + x))*Erf[(1 + x)/
               Sqrt[2]])/2
%F A059480 With offset 2: number of permutations that simultaneously avoid the patterns 
               12-3 and 21-3 and start with 1 and end with 12. E.g.f.: exp(x+x^2/
               2) * {1-int[0..x, exp(-t-t^2/2) dt]} - 1.
%o A059480 (PARI) { a=b=c=1; for (n = 0, 200, if (n>1, a=b + (n + 1)*c; c=b; b=a); 
               write("b059480.txt", n, " ", a); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Jun 27 2009]
%Y A059480 Sequence in context: A020138 A090083 A034515 this_sequence A105723 A143555 
               A025234
%Y A059480 Adjacent sequences: A059477 A059478 A059479 this_sequence A059481 A059482 
               A059483
%K A059480 nonn
%O A059480 0,3
%A A059480 Wouter Meeussen (wouter.meeussen(AT)pandora.be), Feb 15 2001

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