-841

Appears in sequences

• Reversion of rooted trees A000081.at n=19A050395
• a(n) = L(n)*C(n), L(n)=Lucas numbers (A000032), C(n)=reflected Lucas numbers (see comment to A061084).at n=7A075150
• First differences of A014292.at n=21A104862
• Semiprime(n)*semiprime(n+3) - semiprime(n+1)*semiprime(n+2), where semiprime(n) is the n-th semiprime.at n=33A118780
• For all n >= 2, Sum_{2<=k<=n, gcd(k,n)>1} a(k) = 1. a(1)=1.at n=77A124385
• Convolution of A006352 and A010815.at n=35A143278
• Perfect powers (m^k where m is an integer and k >= 2) multiplied by -1 when m is prime for largest k (m^k thus a prime power).at n=37A157985
• Expansion of (1+x+x^2)*(1-8*x^3-14*x^4+8*x^7+x^8)/(1+x^4)^3.at n=28A188477
• Expansion of (1+x+x^2)*(1-8*x^3-14*x^4+8*x^7+x^8)/(1+x^4)^3.at n=29A188477
• G.f.: real part of 1/(1 - i*x - i*x^2) where i=sqrt(-1).at n=20A201837
• First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 347", based on the 5-celled von Neumann neighborhood.at n=15A271300
• G.f.: Re((i; x)_inf), where (a; q)_inf is the q-Pochhammer symbol, i = sqrt(-1).at n=51A278399
• Expansion of Product_{k>=1} (1 - x^k)^(sigma_2(k)).at n=10A288389
• G.f.: Im(1/(1 + i*x/(1 + i*x^2/(1 + i*x^3/(1 + i*x^4/(1 + i*x^5/(1 + ...))))))), a continued fraction, where i is the imaginary unit.at n=25A293269
• Dirichlet g.f.: 1 / zeta(s-2).at n=28A334657
• a(1) = 1, a(2) = -5; a(n) = -n^2 * Sum_{d|n, d < n} a(d) / d^2.at n=28A359485
• a(1) = 1, a(2) = 3; a(n) = n^2 * Sum_{d|n, d < n} (-1)^(n/d) a(d) / d^2.at n=28A361986
• a(1) = 1; a(n) = n^2 * Sum_{d|n, d < n} (-1)^(n/d) a(d) / d^2.at n=28A361987
• a(n) = (n-1)! * Sum_{d|n} (-1)^(d+1) / (d-1)!.at n=7A363736
• Expansion of (1 - x + x^2)/(1 - 2*x + 3*x^2 + 2*x^3 + x^4).at n=10A375275