%I A119881
%S A119881 1,3,8,18,32,48,128,528,512,6912,2048,357888,8192,22351872,32768,1903822848,
               131072,
%T A119881 209865080832,524288,29088886161408,2097152,4951498048929792,8388608,
%U A119881 1015423886523629568,33554432,246921480190140874752,134217728,70251601603944228323328
%V A119881 1,3,8,18,32,48,128,528,512,-6912,2048,357888,8192,-22351872,32768,1903822848,
               131072,
%W A119881 -209865080832,524288,29088886161408,2097152,-4951498048929792,8388608,
%X A119881 1015423886523629568,33554432,-246921480190140874752,134217728,70251601603944228323328
%N A119881 E.g.f. exp(3x)sech(x).
%C A119881 Transform of 3^n under the matrix A119879.
%F A119881 a(n)=sum{k=0..n, A119879(n,k)3^k}
%F A119881 a(n) = Sum(binomial(n,k)*B(k,1)*2^(n+k)/(n-k+1), k=0..n). Here B(k,1) 
               are the Bernoulli number A027641(k)/A027642(k) with the exception 
               B(1,1)=1/2. [From Peter Luschny (peter(AT)luschny.de), Dec 14 2008]
%F A119881 a(n) = 2^n |E(n,-1)| where E(n,x) are the Euler polynomials. [From Peter 
               Luschny (peter(AT)luschny.de), Jan 25 2009]
%p A119881 a := proc(n) add(binomial(n,k)*bernoulli(k,1)*2^(n+k)/(n-k+1),k=0..n) 
               end: [From Peter Luschny (peter(AT)luschny.de), Dec 14 2008]
%p A119881 a := n -> 2^n*abs(euler(n,-1)): [From Peter Luschny (peter(AT)luschny.de), 
               Jan 25 2009]
%Y A119881 Sequence in context: A088589 A063597 A004210 this_sequence A075342 A083726 
               A081489
%Y A119881 Adjacent sequences: A119878 A119879 A119880 this_sequence A119882 A119883 
               A119884
%K A119881 easy,sign
%O A119881 0,2
%A A119881 Paul Barry (pbarry(AT)wit.ie), May 26 2006