131584

Appears in sequences

• Numbers that are the sum of 4 nonzero 8th powers.at n=27A003382
• Number of types of Boolean functions of n variables under a certain group.at n=8A028403
• Number of reversible strings with n beads of 4 colors.at n=9A032121
• Dirichlet convolution of powers of 2 (2,4,8,...) with themselves.at n=14A034713
• Numbers k such that sigma(phi(k)) is a prime.at n=38A062514
• Numbers k such that usigma(phi(k)) is a prime.at n=26A065875
• Numbers k such that the number of divisors of k equals the number of anti-divisors of k.at n=21A073694
• Sum of coefficients of (x1)^(2i(1))*(x2)^(2i(2))*(x3)^(2i(3))*(x4)^(2i(4)) for {(i1),(i2),(i3),(i4)}=0,1,2,... : sum(i)=2n in the expansion of (x1+x2+x3+x4)^(2n) where n >= 1.at n=4A075878
• Numbers k such that phi(k) is a perfect 8th power.at n=15A078168
• Number of closed walks of length 2*n on the 4-cube.at n=5A092812
• Central terms of the rows of the XOR difference triangle of the powers of 2 (A099884) so that a(n) = A099884(n, floor(n/2)).at n=17A099885
• Expansion of g.f.: x*(4-7*x+2*x^2-8*x^4+16*x^5-16*x^6)/((1-2*x) * (1-2*x^2) * (1-2*x+2*x^2) * (1+2*x^2)).at n=16A100213
• Expansion of (4 - 7*x + 2*x^2)/((1-2*x)*(1 - 2*x + 2*x^2)).at n=16A100215
• Triangle P, read by rows, that satisfies [P^4](n,k) = P(n+1,k+1) for n>=k>=0, also [P^(4*m)](n,k) = [P^m](n+1,k+1) for all m, where [P^m](n,k) denotes the element at row n, column k, of the matrix power m of P, with P(k,k)=1 and P(k+1,1)=P(k+1,0) for k>=0.at n=25A111845
• a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) for n >= 4 starting with a(0) = 1, a(1) = 2, a(2) = 4, and a(3) = 6.at n=18A131885
• a(n) = 2^n*(3*n^2 + 13*n + 8)/8.at n=11A136530
• a(n) = Sum_{d|n} phi(n/d)^2*2^d.at n=17A160620
• a(n) = n^5*(n^4 + 1)/2.at n=4A168372
• a(n) = n^10*(n^8 + 1)/2.at n=2A170800
• First occurrence of -n in A220115.at n=8A220118