-297

Appears in sequences

• (n+1)^2*a(n+1) = (9n^2+9n+3)*a(n) - 27*n^2*a(n-1), with a(0) = 1 and a(1) = 3.at n=5A006077
• Expansion of e.g.f. cos(sinh(x)/cos(x)), even powers only.at n=3A009064
• Expansion of Product_{k>=1} (1 - x^k)^9.at n=22A010817
• Expansion of Product_{m>=1} ((1+q^(2*m-1))/(1+q^(2*m)))^3.at n=26A029840
• a(n) = floor(Sum_{k=0..n} tan(k)).at n=42A051508
• a(n) = floor(Sum_{k=0..n} tan(k)).at n=45A051508
• a(n) = round(Sum_{k=0..n} tan(k)).at n=42A051509
• a(n) = round(Sum_{k=0..n} tan(k)).at n=45A051509
• a(n) = ceiling(Sum_{k=0..n} tan(k)).at n=48A051510
• McKay-Thompson series of class 44a for Monster.at n=25A058680
• Expansion of (1-x-x^N)/((1-x)(1-x^2)(1-x^3)...(1-x^N)) for N = 10.at n=35A060029
• Triangle of numerators of Integral_{x=0..1} LegendreP(m,x) * LegendreP(n,x) dx.at n=70A078297
• Differences between A097598 and A045918.at n=30A097846
• Riordan array (1,c(-x)), where c(x) = g.f. of Catalan numbers.at n=39A099039
• Expansion of (1+x^2)^2/(1+x^2-2x^3+x^4+x^6).at n=20A099493
• Third convolution of A115140.at n=8A115142
• a(n) = a(n - 1) - 2*a(n - 2) + a(n - 3) - 2*a(n - 4) + a(n - 5).at n=24A122582
• a(n)=the (1,1)-term of M^(n-1), where M=matrix(5,5, [3,-1,-1,-1,-1; 1,3,-1,-1,-1; 1,1,3,-1,-1; 1,1,1,3,-1; 1,1,1,1,3]).at n=5A123220
• Triangle read by rows: T(0,0)=1; for n>=1, 0<=k<=n, T(n,k) is the coefficient of x^k in the characteristic polynomial (-x)^n+... of the n X n matrix M(n)S(n), where M(n) is the n X n matrix with 0's on the diagonal and 1's elsewhere and S(n) is the n X n matrix whose (i,j) term is 0 for j=i, (-1)^(i+j) for i>j and (-1)^(i+j+1) for i<j.at n=82A126595
• Sequence is identical to its third differences in absolute value: a(0), a(1), a(2), a(2n+1)=3a(2n)-3a(2n-1)+2a(2n-2), a(2n+2)=3a(2n+1)-3a(2n), with a(0)=a(1)=0, a(2)=1.at n=17A131665