Search: id:A002436
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%I A002436 M3701 N1512
%S A002436 1,4,80,3904,354560,51733504,11070525440,3266330312704,
%T A002436 1270842139934720,630424777638805504,388362339077351014400,
%U A002436 290870261262635870715904,260290690801376575335956480
%N A002436 E.g.f.: Sum_{n >= 0} a(n)*x^(2*n)/(2*n)! = sec(2x).
%D A002436 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A002436 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A002436 A. Fletcher, J. C. P. Miller, L. Rosenhead and L. J. Comrie, An Index 
               of Mathematical Tables. Vols. 1 and 2, 2nd ed., Blackwell, Oxford 
               and Addison-Wesley, Reading, MA, 1962, Vol. 1, p. 75.
%D A002436 Glaisher, J. W. L., Quart. J. Pure Appl. Math., 44 (1913), 105-112.
%F A002436 4^n * A000364(n).
%p A002436 A := n -> (-4)^n*euler(2*n); (Then A(n) = a(n+1) for n >= 0.) [From Peter 
               Luschny (peter(AT)luschny.de), Jan 27 2009]
%o A002436 (PARI) a(n)=if(n<0,0,4^n*(2*n)!*polcoeff(1/cos(x+O(x^(2*n+1))),2*n))
%Y A002436 Cf. A002436(n)=A000831(2n).
%Y A002436 Equals 2 * A000816(n-1), n>1.
%Y A002436 Sequence in context: A012824 A012057 A102063 this_sequence A013031 A012923 
               A012922
%Y A002436 Adjacent sequences: A002433 A002434 A002435 this_sequence A002437 A002438 
               A002439
%K A002436 nonn,easy,nice
%O A002436 1,2
%A A002436 N. J. A. Sloane (njas(AT)research.att.com).
%E A002436 More terms from Michael Somos, Jun 21, 2002

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