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 A180960 A generalized Narayana triangles for sec(x)^2 (or Zag numbers). 0
 1, 1, 1, 1, 4, 1, 1, 9, 9, 1, 1, 16, 46, 16, 1, 1, 25, 150, 150, 25, 1, 1, 36, 375, 952, 375, 36, 1, 1, 49, 791, 4039, 4039, 791, 49, 1, 1, 64, 1484, 12992, 31078, 12992, 1484, 64, 1, 1, 81, 2556, 34524, 162774, 162774, 34524, 2556, 81, 1, 1, 100, 4125, 79920, 641250 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS FORMULA G.f.: 1/(1-x-xy-1*2*x^2y/(1-x-xy-2*3*x^2y/(1-x-xy-3*4*x^2y/(1-...(continued fraction); E.g.f.: exp((1+y)x)*sec^2(sqrt(y)x); T(n,k)=sum{j=0..n, C(n,j)*C(n-j,2(k-j))*Z_(k-j)}, Z_n=A000182(n+1). EXAMPLE Triangle begins 1, 1, 1, 1, 4, 1, 1, 9, 9, 1, 1, 16, 46, 16, 1, 1, 25, 150, 150, 25, 1, 1, 36, 375, 952, 375, 36, 1, 1, 49, 791, 4039, 4039, 791, 49, 1, 1, 64, 1484, 12992, 31078, 12992, 1484, 64, 1, 1, 81, 2556, 34524, 162774, 162774, 34524, 2556, 81, 1, 1, 100, 4125, 79920, 641250, 1484504, 641250, 79920, 4125, 100, 1 CROSSREFS Cf. A180959. Sequence in context: A124216 A008459 A259333 * A157192 A154982 A146767 Adjacent sequences:  A180957 A180958 A180959 * A180961 A180962 A180963 KEYWORD easy,nonn,tabl AUTHOR Paul Barry, Sep 28 2010 STATUS approved

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Last modified September 21 13:37 EDT 2019. Contains 327253 sequences. (Running on oeis4.)